He walks up to the bartender, orders a drink, and sips it while socializing with a couple of the regulars. He leaves before he's even finished his drink. The regulars agree he was nice, but a little off.

10 minutes later, Jerry Banfield walks back into the same bar. This time, he has a friend and gives them a hearty clap on the back as they approach the bartender. The friend gets a drink and Jerry leaves again.

10 minutes later Jerry Banfield walks into a bar - this time, with 2 friends. They're all smiles and laughs. Jerry buys them both a drink, congratulates them, and leaves.

10 minutes later, Jerry Banfield walks into the bar with 3 friends. He buys them all drinks and introduces them to the friends he previously came in with. This new troup interacts strangely with the regulars. They struggle to order their own drinks, and usually wait for Jerry to help them with it.

10 minutes later, Jerry Banfield walks into a bar. He has only one friend with him. They sit in a quiet corner for 3 minutes talking in hushed tones while Jerry makes grand, sweeping gestures with his arms. This new friend joins the previous friends and starts explaining to them how to interact with the regulars and how to order drinks. Jerry smiles at them all on his way out the door.

10 minutes later, Jerry Banfield walks into the bar. No friends this time, but he hops up on the bar, waves his arms, and requests that everyone look at him. He explains to all that he has recently showed people how to order drinks. With great passion, he explains that ordering drinks can be done by anybody. He proposes everyone in the bar gives him all their money so they can order even more drinks together. He further offers personal drink consulting for $799 per minute. His friends start clapping and gushing over how great he is. Most of the regulars are just confused as to why he is there - some wonder wtf is wrong with these people....
..................
Shit! I forgot the joke part. Uhm..... Jerry is in AA.... so.... ok here:
Jerry Banfield walks into a bar, he says "oh whoops" and leaves. The crowd goes wild.