modern slang for someone successfully being cool. From penile-drip (can be vaginal). A sexually transmitted disease often results in penile drip, young adults now brag about this, since it proves they (likely) had sex,thus are now "cool".
Yo, check out my drip, because I scored, I'm rad. boo-yah!
Oh yeah? That's nothing! I got the herpes, now you know I got some action!