The creamy spooge that runs down a girls inner thighs/legs when she stands up too quickly. She has received too big a load from Studly Do Rite and it has to escape her man chops.
Example: Jen don't get up too fast after I fill your twat with my spooge else you'll have a case of Leg Jelly. You know if that happens, I'll have to do you in the behind sose to get some peanut butt-er and make you a peanut butt-er and Leg Jelly sam'ich! Mmmmmm Yummy!