Both of them!

A guy stops by to visit his friend. They talk for a while and then the friend asks, "My feet are cold. Would you be so kind as to go get me my sneakers please?" The guest obliges and goes upstairs. There he sees his friends daughters, both very good looking.

Being the adventurous and quick thinking kind, he says: "Hi, ladies! Your daddy sent me here to have sex with you!"

They stare at him and say, "That cant be!"

He replies, "OK, lets check!"

He shouts at his friend down the stairs, "Both of them?"

"Yes, both of them!"