Murphy calls in to see his mate Paddy, who has a broken leg.
Paddy says, "Me feet are freezin', mate, could you nip upstairs and get me slippers?"
"No bother" says Murphy. He runs upstairs, and there are Paddy's two stunning 19-year-old twin daughters sat on their beds.
"Hello dere, girls. Your Da's sent me up here to shag ye both."
"Fook off, you liar!"
"I'll prove it" says Murphy. So he shouts down the stairs:
"Both of them, Paddy?"
"Of course! What's the use of fookin' one?"