Doug Stanhope has never been a comedian to shy away from material that might shock or offend. The more notorious the tale, the more likely it has been sourced from his own first-hand experiences of life on the road. Largely unprintable encounters about a Thailand strip club entertainer called the Banana Lady or the time he got into a brawl with a transvestite prostitute in Phoenix or the weekend he had the nonagenarian boxing legend Jake LaMotta over to his home on the US-Mexican border are typical Stanhope: brutal, icky, forensically detailed and, above all, ferociously funny.

But even he must have balked over telling the most difficult story of his career: the 2008 suicide of his 63-year-old mother Bonnie. Suffering from emphysema, she chose to end it all with a heavy cocktail of Black Russians and prescription morphine. Stanhope was present at her death, turning what could have been a sombre event into a comedy roast and film night (they watched her favourite movie, Bad Santa). The evidence is in his most recent DVD (also available on Netflix), Beer Hall Putsch.

“I can’t think of a better way to go out than with cocktails and jokes,” the 48-year-old comic insists. “I wouldn’t want a bunch of weepy relatives sitting around crying and holding my hand in a hospital room waiting for the inevitable without knowing when it’s going to happen. It was difficult to make that routine work; not from any point of view of it being painful for me, it was just a matter of making it funny so that it doesn’t outright depress people. It was all about getting it to a format where it was stage-friendly.”

Stanhope is not exactly a ‘greatest hits’ comic, so it’s unlikely that he’ll retell this story when he’s in Scotland at the beginning of October. Indeed, when we chat over the phone in mid-September he seems unclear as to anything his shows will feature. “I have stuff to talk about but it doesn’t mean that’s what I’ll be doing. Unlike other years, I’ve come to the UK and had to scramble around for another half hour when I realised that some stuff just won’t work overseas. I think I’ve finally worked it out; the last three countries I’ve played were Australia, New Zealand and Canada so I know I’m keeping my shows more universal.”

You might have assumed that the current race for the Republican and Democratic nominations ahead of the 2016 presidential election would have engendered plenty comedic material, but for Stanhope this would be too easy (the comic himself was intending to run in the 2008 poll as an independent Libertarian candidate before issues of financial restrictions led him to pull out).

“I know that everyone will be waiting for my Donald Trump material and as amusing as he is, I wouldn’t even try to write jokes about him. There’s no angle; he is what he is. You see a lot of bad comics doing their ‘news of the weird’ jokes: ‘did you see this thing where a guy tried to have sex with a vacuum cleaner?’ Well, it’s already inherently funny so I’m not sure what you’re going to add to that. It’s cheap and it’s cheating.”

Doug Stanhope has been performing his own brand of non-cheating, visceral stand-up since the early 90s. An extra on the 2004 Deadbeat Hero DVD shows some of his initial recorded work, drink in hand, mullet on head, the self-assurance of someone who was clearly born to be on a stage already evident as he delivers risqué material about his sex life.

“My mother was a huge inspiration and we shared a very caustic sense of humour. They thought I was psychotic in school and wanted me to see psychologists and counsellors; everything that I’m known for now was apparent at 11 years old and was not welcomed. They didn’t get the joke. Fortunately my mother was a hoarder so I can still see the homework assignments where I’d written horrible things which I’d even look back at now and realise were very dark.”

Stanhope’s trail to cult status has included him being inevitably hailed as the "new Bill Hicks", appearing in The Aristocrats movie where he told his version of the titular jet-black joke to a baby, waging an unpleasant online war with columnist Allison Pearson over the right to die and appearing in both Louis CK’s sitcom and Charlie Brooker’s Weekly Wipe as the ‘voice of America’. More recently, there have been rumours that he’s about to launch into a new TV project alongside Johnny Depp: “I was hanging out with him when he was filming Mortdecai and we kept saying, ‘yeah we really ought to do that’. It’s just like any other great idea that you probably never really get round to. I’ve got books full of stuff like that.”

As well as the two dates he’s performing at Glasgow’s O2 Academy, he’s been booked for a night at the intimate venue where it all started in Scotland for Stanhope. In 2002, he debuted at the Edinburgh Fringe in the basement of the Tron bar in Hunter Square, rolling home with a clutch of rave reviews and the beginnings of a passionate fanbase which has bloomed over the subsequent years.

“I really enjoy that room. One of the times I played there I felt the most ill I’d ever been. The place I was staying in was directly across the street and I was basically carried to the stage and sat there sweating like Elvis trying not to pass out for an hour. I went directly back to bed for another 23 hours before it all started again.”

He has returned to Scotland on several occasions, and in 2007 he made Go Home, a half-hour Channel 4 documentary about immigration in which he questioned a BNP candidate canvassing outside Ibrox Stadium and met Polish workers at a potato factory near Perth, all of which was intercut with his stand-up on the subject.

Areas like immigration is moth-to-the-flame stuff for Stanhope. The thornier the topic, the more valid it is for his own brand of enquiry: fearless, brazen and always original. His particular takes on issues such as cancer charities, over-population and "supporting the troops" are as incisive as they are uncomfortable.

An early-career mantra for Stanhope was that there was little difference between having an adventurous spirit and being dubbed a "sicko". It was always about context and where to draw the line. “I’m a settled home owner now and the adventures are far more timid than they used to be. On stage, the stories are perhaps a little more morose; suicide has taken the place of good hooker stories, and dealing with death comes up more. I have gotten old. My adventurous spirit these days is putting a new kind of hot sauce on my eggs before the game starts.”

Doug Stanhope is O2 Academy, Glasgow, Friday October 2 & Saturday October 3, with an intimate warm-up gig at the Tron, Edinburgh, Thursday October 1. Tickets for the Edinburgh show are available from www.brownpapertickets.com/event/2327717