Can someone explain this joke to me, I don't get it, man

This dirty joke told by my favorite, Paul Mccartney, man

YouTube - Paul McCartney Tells a Dirty Joke

Please explain it to me, man, I am smoking a fat J right now, man

They call the bartender a goat fucker ?_?

Shit iunno

Yea I think everyone calls him john the goat fucker or somthing... I never understood british comedy

Yeah it's a shit joke, made all the worse by his terrible delivery. It's basically saying he fucked one goat and thats all he's known for even though he can do so many other things really well.

He should stick to the day job.