Late Night Proposition

One night a guy takes his girlfriend home. As they are about to kiss each other goodnight at the front door, the guy starts feeling a little frisky. With an air of confidence, he leans with his hand against the wall and smiling, he says to her, “Honey, would you have sex with me?”
Horrified, she replies, “Are you mad? My parents will see us!”
“Oh come on! Who’s gonna see us at this hour?” he asks, grinning at her.
“No, please. Can you imagine if we get caught?”
“Oh come on! There’s nobody around, they’re all sleeping!”
“No way. It’s just too risky!”
“Oh please, please, I love you so much!”
“No, no, and no. I love you too, but I just can’t!”
“Oh, yes you can. Please?”
“No, no. I just can’t”
“I’m begging you.”
Out of the blue, the light on the stairs goes on, and the girl’s older sister shows up in her pajamas, hair disheveled, and in a sleepy voice, she says:
“Dad says to go ahead and have sex with him, or I can do it… or if need be Mom says she can come down herself and do it. But for heaven’s sake, tell him to take his hand off the intercom!”