Many Americans aren't familiar with Boyle, but across the Atlantic, the comic is notorious for his disregard for boundaries. His repertoire reads like a laundry list of dumb shit, or the lunch-room banter of middle school boys: He’s poked fun at disabled athletes participating in the Paralympics; he’s said made offensive remarks about the Queen; and he’s performed routines about those suffering from Down syndrome. It goes without saying that his sets frequently involve potentially racist and sexist material.
Because of these things, he's faced the BBC numerous times over allegations that his jokes are too offensive to be broadcast. Naturally, it doesn't appear to have hurt his career much (a 2011 libel lawsuit against The Mirror, accusations of tax evasion, and a 2013 set that was entirely cut from the BBC broadcast of a charity event, notwithstanding).