A bloke goes into a bar and orders a pint. he takes a sip of his drink and puts it down, suddenly a little alien runs along the bar and jumps into his beer and waves his arms shouting blah.
Then the alien runs off. the bloke thinks nothing of it and takes another sip and puts his glass back down. the alien then comes back, jumps in the glass, waves his arms and shouts blah, jumps out again and runs off. the bloke then thinks, right the next time he does that I'll get him.
He takes another sip of his drink puts it down and waits. Sure enough the alien comes back jumps into the glass, and the bloke then catches him. he looks at the alien and says "if you do that again I'll chop your privates off" the alien says" I ain't got any" the bloke goes "well how do you go to the toilet then" and the alien waves his arms and shouts blah.