Seven seems to be the magic number:
"I could introduce you to Dobby, if you're interested."
"Expelliarmus, baby. You can't resist Severus Snape."
"On the Marauder's Map, I have a really big... icon."
"Here, sample my stash of -- oh wait, that's gillyweed."
"Accio seduction music!"
"Ooh, the Head Girl of Hufflepuff. You must be good at [censored]."
"So tell me... is there a Mr. McGonagall?"
Variations and contributions are welcome. Try not to get too dirty.