[stolen shamelessly from the Mensa website]
A man enters a bar with a 6-inch amphibian perched on his shoulder.
The bartender (as is the norm with these jokes) asks, "What'll it be?"
"A pint of Guinness for me, and another pint for Tiny here," he says, pointing to his shoulder.
"You call him 'Tiny' because he's small? He looks pretty big for a salamander..."
The man laughs and says "No, I call him 'Tiny' because he is my newt."