Work experience, much like puberty, is a great way for teenagers to enjoy their first taste of the horrors of the adult world. Usually, it's an efficient way to experience one job, so you know you definitely won't do it when you're older. My cousin, for example, worked at a vet's practice. One day, when the vet went out to buy a chocolate bar, a parrot keeled over and died, taking with it to the grave any ambitions my cousin held of working with animals. I, on the other hand, spent a week working for the Augsburg Police Department, in Bavaria, Germany.

As was the case with my cousin, rather than spurring me into a successful career in law enforcement, I now campaign for the decriminalisation of drugs. This is, in part, due to what I learned in my time as a policeman.

I don't know how most people end up working for the police, but for me it was through incompetence and panic. It was while I was studying for my German AS Level at Cherwell School in Oxford. We were told to think about what we each wanted to do on our yearly work experience trip to Augsburg. I'd forgotten to do any thinking about it, so when my teacher went around the room and asked us all, I panicked and said the coolest thing I could think of. "Police." And that's where I ended up. Like a real-life McLovin.

I was staying with the family of a girl who went to our partner school, whose dad worked for the police. However, he told me on the first day that he worked in fraud, which is quite boring, so he suggested I spent some time with the guys in the anti-drug squad, because they saw a lot more action.

This turned out to be very true. On my first day, immediately after dropping my exchange partner at school, we arrested one of her fellow students right outside for selling weed. We took him back to the station for questioning, where my "colleagues" told me that, seeing as I didn't speak much German, I could be bad cop. I just had to sit in the corner of the room and look mean, to intimidate him into giving us the name of his supplier. This was no easy task, seeing as I was rocking this look at the time:

Mind you, I must have looked pretty terrifying because the guy grassed on his dealer in almost no time. We drove to the address provided, on the outskirts of town – a full squad of ten police officers, dressed in bulletproof vests, with guns, and me, dressed pretty much exactly the same as in the picture above. As we approached the apartment I was put at the back of the line, for my own safety, but due to an administrative error – we went up too many flights of stairs, to the wrong flat – I ended up at the front of the line, and first to the door.

No one was home so they kicked the door in, screaming, "Polizei!" I ambled along behind with my hands in my pockets, with their expressed permission to help them search the flat. The policemen I was with were obviously better at it than me, because they managed to find a stash of heroin and other drugs fairly quickly. I managed to find a stack of hardcore pornography. As a virginal teenager, that's what I'd been trained for. Before going home we made a quick stop to arrest one of the people who was registered to live at the flat, at her job in the local supermarket, and then headed home. My first day was over.

It was during my time with the police that my attitudes towards drugs and drug laws really started to change. Before then, I'd always subscribed to the inherited wisdom that if you ever took drugs you were a loser, and that drugs were evil. Yet, the policemen I worked with – while very good at catching criminals – didn't seem to believe in the laws they were upholding. They told me that every dealer they arrested was immediately replaced by another, and that addicts never got the help they needed and always ended up back on the streets. They were fighting a pointless, losing battle, and their time would be much better spent solving other crimes, they said.

Training day was probably the most fun I had, largely because I was in the least danger. I was taken to an actual Police Academy and given a day of refresher courses. First, there was martial arts class, which should be fairly self-explanatory. Then we had a class in which we were taught useful bits of info, like what happens if a bullet hits your Kevlar when you have a metal button underneath it (you're fucked), or what happens if it hits your police radio first (you're super fucked). We watched some slow-mo videos of bullets hitting melons and poor, rubber men. They taught me how to break out of handcuffs, and then they took me outside and set a huge Alsatian on me.

Finally, I was allowed to play around on the academy shooting range. I was given a Heckler Koch pistol and an MP5 submachine gun and let loose on a projected video of men jumping out from behind barrels and shooting at me. It was like a live-action Time Crisis, and one of the best afternoons of my life. I have to say, a part of me can see why so many Americans are opposed to gun control, because guns are really good fun. It's such a shame that their primary function is to kill people. If they only worked on tin cans and bottles they would be absolutely superb.

"As we were leaving the pub one of the officers noticed something fishy about a guy coming in, who'd made a runner down the street. They gave chase, tackled him to the ground, reached into his jacket and threw me what I later found out was €30,000 worth of heroin."

On my penultimate day, my police friends wanted to show me what German court proceedings are like. We drove down to the Augsburg courthouse, but unfortunately, after a couple of hours of waiting, it became clear that the defendant had jumped bail and wasn't going to show. My colleagues were very disappointed, and bored, so they decided to take me on an impromptu raid of a pub in the centre of town that, in their words, "always had dodgy people hanging around".

I'd always thought that drug raids were carefully planned affairs, but apparently not. It's just something to do, to kill time. Three officers and I stormed the place at around lunchtime. They were armed with pistols and torches; I had a Nokia 3310 and a pretzel I'd bought on the way. There was an awkward moment when I made eye contact with the Latvian sex worker I'd taken mugshots of a couple of days before, but otherwise it was uneventful. However, as we were leaving the pub one of the officers noticed something fishy about a guy coming in, who'd made a runner down the street. They gave chase, tackled him to the ground, reached into his jacket and threw me what I later found out was €30,000 worth of heroin.

I had the mother load and was allowed to hold onto it as we drove back to the station. At some point, the man we'd arrested (who, for some reason, I was sharing the back seat with) found out that I was only 17 and still at school. He'd assumed I was a visiting English policeman and was mortified, not to mention very worried about what being arrested by a schoolboy would do to his street cred. Our bust made the local paper a few days later.

My time in the German police force gave me some very niche German vocabulary and enough pub stories to last me the next 12 years. I definitely learnt a lot from my work experience. It completely changed my career trajectory, personally starting me on the path to recreational drug use and a deeply held conviction that all drugs should be legalised. I now campaign for the decriminalisation of drugs, and my new stand-up comedy show all about legalisation will be debuting at the Edinburgh Fringe this summer.

Oh, that, and I know how to say "gear" in German now.