I once went to see Bernard Manning and I laughed so much it hurt. It was the night he died.

No, it wasn't. It was during my days as a provincial hack, when Manning had come to do a show, I was offered review tickets and I went out of idle curiosity. Turning up a little late, Manning wheezed onto stage -- he was in his 70s -- and complained about how he'd got his Rolls Royce lost in Tooting.

"It's full of fucking Pakis there, isn't it?" he roared, and you could sense the relief and joy in the room. Yes, we were going to get our racist jokes. All was going to be right with the world. Here we were, in a safe place from nascent political correctness, which was already going mad.

I did laugh a lot at his jokes at first. Manning, whatever else you think of him, had great comic timing, and some of the material was funny.

I say this, as you know, as a fully paid-up member of the PC Brigade and the fun-hating Left (capital L essential). But about halfway through, I found I wasn't laughing so much. Bernard packed the second half of his act with more and more (badly crooned) songs; even after a lifetime in the business, his material didn't stretch to more than an hour. Because there came a point when, having heard gag after gag in which the Jew, the Paki, the nigger, the woman or whoever was on the receiving end, it became pretty predictable. And you got the sense that he knew that himself.

Which brings me to Ricky Gervais. After tweeting a picture of his "mong face" the other day, he unleashed a gentle tornado of disapproval. Many condemned him for the use of the word; others were disappointed with his behaviour afterwards, in which he claimed that "haters" were just jealous of his success.

Richard Herring, who knows a sight more about comedy than I do, wrote a well-crafted blogpost about why it jarred with him.

It jarred with me too, not because of the word itself but because, as was the case with Bernard Manning, there can come a point where offensive jokes stop being funny, where the situation shifts and it begins to look like simple trash talk, of one stronger person picking on a weaker person. For me, the time when Gervais's followers started berating anyone who had taken offence was when it stopped being funny, if it ever had been.

I'll put my hand up now for the avoidance of doubt and say I like offensive jokes. On his most recent tour, I saw Jimmy Carr complete a night of brilliant gags with an encore in which he tested his audience by telling increasingly shocking jokes. It culminated with a one-liner so extraordinarily filthy that I really can't repeat it here -- suffice it to say it was truly vile and unpleasant. And hilarious. But your mileage may vary. You may have sat through it in stony silence, horrified, wondering why on earth anyone would find that amusing. Not me; I loved it.

I think comedy can be about testing boundaries and revealing to ourselves the prejudiced, awkward, dark and downright unpleasant folk we sometimes are deep down inside.

Whether it's Frankie Boyle mocking the weak or Stewart Lee honing a typically convoluted riff about wanting to see Richard Hammond decapitated, it makes me laugh. Look back at now revered classics like Derek and Clive or The Producers, and there are still parts that should -- and do -- make you wince. But I find myself laughing, too.

And one of my all-time favourite moments of TV -- Alan Partridge temporarily escaping from his crazed stalker, Jez -- relies on the line "No way you big spastic, you're a mentalist!"

So what's the difference there between Partridge's "spastic" and Gervais's "mong"? Why do I find one funny and the other tragic? I think it comes down to a question of tone. Partridge is berating someone who's tried to imprison him, and you can forgive his use of the playground slur as a punchline; with Gervais there is no set-up, there's just a punchline. Mong. I look like a mong! Mong. That's all there is to it.

True, some people do go out of their way take offence, others can't help being offended, and others aren't offended at all. I tend to fall into the latter category when it comes to comedy, but that doesn't mean I can't see understand why people are upset, offended and dismayed by certain jokes. Sometimes, no matter how careful you are, you're going to hurt others' feelings.

Sometimes that's a price worth paying for a laugh, and sometimes it isn't.