Boyfriend embarrassment

One night a guy takes his girlfriend home. As they are about to kiss each other good night at the front door, when the guy starts feeling a little horny.

With an air of confidence, he leans with his hand against the wall and smiling, he says to her:
-Honey, would you give me a BJ?

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 please... I love you so much?!? - he doesn't stop persuading her.
-No, no and no! I love you too, but I just can't!
-Oh yes you can. Please?- the boyfriend is desperate.
-No, no. I just cant....
-I'm begging you?...

Out of the blue, the light on the stairs goes on, and the girl's sister shows up in her pajamas, hair all messed, and in a sleepy voice she says:

-Dad says to go ahead and give him a BJ, or I can do it. Or if need be, mom will do it, or even dad. But for God's sake tell him to take his f***ing hand off the intercom!!!