A guy, named McKenzie Robertson, walks into a bar. Before I forget, I better tell you that the guy's name isn't important, but the fact that the bar is in England may be, you'll have to read on to figure out if it is though. Anyway, McKenzie orders a pint and a pork pie, downs his pint, puts the pork pie on his head and smashes it with his hand, then walks out, leaving the barman a little confused.
The next day McKenzie comes back in, orders a pint and a pork pie, downs the pint, puts the pork pie on his head, smashes it with his hand and walks out, leaving the barman even more confused. The barman's name, by the way, is Leo.
The next day McKenzie comes in again and orders a pint and a pork pie but the barman, trying to figure him out, says "sorry, no pork pies." So, McKenzie orders a packet of cheese and onion potato chips (which are called "crisps" in England, like it makes a difference anyway), downs the pint, puts the packet of cheese and onion chips on his head smashes them with his hand and is about to leave when the barman stops him and asks "why did you just smash that packet of cheese and onion chips on your head?" and McKenzie replies, with a big toothy grin, "because you didn't have any pork pies."