A flap jacket is a condom, but not just any condom... You must refer to pussy as flap in order to call a condom a flap jacket.
Flap :: Pussy
Flap Jacket :: Condom
"My roommate was digging through all my drawers, cause he was out of flap jackets"
"Melissa might be a keeper. She doesn't mind football, loves Old Chicago and doesn't make me wear a flap jacket"
A hip alternative to pussy, box, snatch, and cutty. Flap refers to more than just the beef curtains, it covers all areas of one's womanhood.
"Me and DeAndre about to hit the town scouting for flap"
"I creased that flap last night dawg, and I didn't even have to wear a flap jacket"