Oh yeah, the best way to get someone to want to do something is to tell them they can't. Put up a "don't jump off this cliff" sign and you'll have them leaping off in droves because fuck that sign.
Lol, it's just a little joke based on the fact that Ancient Greek had both formal and informal greetings, and 'sup is our modern equivalent of an informal greeting. It's quite a stretch, I admit.
cha-cha-cha