Tweeping is when an adult male or female aged 25 years or older likes to hang out with tweens or teens of the opposite sex, for long periods of time, and usually late at night. This is especially creepy, since most adults at that age like to hang out and party with actual adults. Another sense of the word would be tweeper, or tweeps.
EX1: Hey Jordan, wanna go to Michael's house tonight?
No, I think I'm tweeping at Denny's instead.
But their food sucks!
Dude, I wanna hang out with my tweeps!
EX2: Jordan, Ashley is too young for you, you're a total tweeper, and hangin out with those tweeps is a little strange, don't ya think?
Whatever dude, I'm not a tweeper, and those tweeps are as legit as they come. Screw you!