The mermaid at the bar told me this one...

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 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 blow job?"
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?"
Out of the blue, the light on the stairs goes on, and the girl's sister shows up in her pajamas, hair disheveled, and in a sleepy voice she says,
"Dad says to go ahead and give him a blow job, or I can do it. Or if need be,
Mom says she can come down herself and do it...
But for God's sake tell him to take his hand off the intercom!"