A gamer term in the same vein as "a winner is you", "full of win" is a positive descriptor of a person or thing. Things or people that are "full of win" are likely to be victorious in contests or comparisons of popularity, humor, quality, game score, etc.
The new Konami game is so full of win! It's sure to be a best-seller.
A phrase which, when said about a person, indicates that this person is allocating funds from some public treasury (the government, their work, and so forth) for their personal use. Also sometimes said as having one's "hand in the till."
Q: "How can Rod Blagojevich afford to buy that new yacht?"
A: "Oh, he was known to dip into the till quite often while he was governor of Illinois."
"Stacy got fired from her job as a bartender because she was caught with her hand in the till."
"Secret Single Behavior." A term originating from the television show Sex and the City, a SSB is an action or habit that one indulges in only when alone. This refers especially to behavior that is hidden from one's significant other and could be potentially embarrassing (or disastrous) if discovered.
My personal SSB is eating a half-gallon of chocolate ice cream for dinner. I also dance around the apartment in underoos.