Any version of "What's So Funny 'Bout Peace Love and Understanding" would have done the trick but, for authenticity's sake (cos we all like a bit of authenticity round here, right?), I've gone for Brinsley Schwarz: http://www.youtube.com/watch?v=ZkuEBHMCOyY
I'll think of some more later. Please feel free to add your own pub rockin' favourites as well
Mine's a pint of bitter etc etc