An unoriginal choice, but the Guinness surfer advert. The leftfield track was inspired. In fact, all the Guinness adverts are frankly awesome. I cannot think of a company that does better adverts.
But what really annoys me is how bar staff invariably do not pour guinness correctly and how it's always better in cans now it's brewed in (or imported directly from) Dublin. If there's one thing that's likely to push me over the edge into the depths of unmitigated violence towards human-kind it's that. Ireland is actually one of the countries I'm most likely to settle in if I do not stay in England for that very reason.
This man has a good list of adverts. Either I didn't get that hula-hoops advert (it's funny because he's not an actor and doesn't really want to be in this advert apparently?) or it just wasn't that funny.