Gratuity is Greatly Appreciated

I like teenagers, don't get me wrong. I just wish they weren't so cheap. Or maybe just broke. Except you in the head-to-to Diesel. Yes you, Mr. Cota De Caza with the rich dad and the blond-highlighted milf for a mom. Tip, dammit.
Yes I know energy drinks are expensive. yes, I too feel that it's outrageous that the candy bars are two bucks.
I need something cute to write on my tip jar:

"Pay up luvs, I'm as broke as you are, only my mommy and daddy don't give me an allowance and I've gots bills to pay."
Bit long? Yeah, too much.

"Because I'd tip you if you were me"
eh, getting there

How about
"I know. The economy sucks. But you don't have to."
Hmm that could be horribly misread, I think. Bah. Too much redbull, not enough sleep...

Don't be a sucker. Tip the girl who's just fished out your cellphone a dozen times only to put it right back into coat check, and got you extra cups of ice for your water. Seriously.
Sometimes, during my occasional gig running concessions for an all ages dance club, I like to imagine that instead I'm a bartender, and that any moment now some drunk is going to give me a tip bigger than the amount of his cocktail. But hey. It's still money I wouldn't have otherwise, and the social climate is awkward enough to be entertaining.