Rhymes with (souvenir); This is something, a personal item, that you take with you after a night of wild lovemakin', after a booty call, or a one-night-stand. You take these things without the original owners' knowledge. It could be a t-shirt, cd, lighter, hairbrush, etc., that belonged to the person you just hooked up with. Sort of like a 'souvenir' of the encounter.
"How do you like this cool candle holder? It's a screwvenir from the other night at Todd's house."