A bloke pops round to visit a sick mate who has a broken leg.
"Anything I can do for you, mate?" he asks.
"My feet are freezing cold, mate," his friend replies. "Can you go and get me my slippers from upstairs please?"

The bloke goes upstairs and finds his mate's gorgeous, sixteen-year-old identical twin daughters in the bedroom, stark bollock naked.

"Hi, girls," he says, looking them up and down appraisingly. "It's your lucky day."
"Watcha mean?" said the first daughter, hurriedly slipping into a black, lace thong and bra while her sister covered herself with a towel.
"Your dad sent me up here to shag the arse off you," said the bloke.
The first daughter says, "Fuck off! He never did."
"He did too," replies the bloke, unzipping his trousers.
"No he never," said the second daughter, clutching the towel tightly to her heaving breasts.

"Oh yes he did," insisted the bloke, "want me to prove it?"
"Go on then," taunted the first daughter, staring boldly at him.
"Both of them?" the bloke yells down the stairs.

His mate yells back, "Of course, both of them! They're a pair aren't they?"