when its really hot out and you're wearing boxers, so your balls are sagging and your thighs are sweaty. this causes your balls to stick to the side of your leg, creating a very awkward situation that always need to be fixed.
Man #1: "Dude, why you keep awkwardly tugging at your balls?"
Man #2: "My balls are all sweaty. I've got some serious stickage"
The part or percentage of a liquid that remains stuck on the inside of a: container, bottle, plastic bag, cup that you can't get out without destroying what you are after.
It's impossible to get all the ketchup out of a ketchup bottle, there is always some stickage left there at the end, so you never get the full amount. The same with tomato sauce in jars, and liquid medicine - some always sticks to the bottom and sides.