My favourite, which appeals to my sense of humour the most, are the monster.co.uk ads.....
don't listen to the voices......... they've been on a while now but they still make me LOL
My worst is..... i don't even want to think about it...... is that fast food ad, some chicken burger thing i think, where the guy sings to the woman asking for a bite of her burger (ooer misses) and she opens her gigantic mouth and starts wailing a response....
I've usually switched off in horror by then so couldn't tell you what it was for....... that advert actually hurts