In all seriousness though, saying "what's your game" is normally something a cowboy says when he's provoked or offended by what someone is doing or saying and another common phrase that's said rather than "what's your game" is "what're you playing at, boy" and you gotta lay alot of emphasis on the "boy". Really they can also mean the same thing as "what in tarnation" but essentially the phrases (excluding "what in tarnation") mean what are you doing.
Person: I just think that's not true
Cowboy: what's your game?
Person: I don't believe you
Cowboy: what're you getting at, boy?
The sexual act of placing both fists into at least one orifice of your partner in a gesture of celebration.
It does still count if you put it in two separate partners.
The teaser, the pleaser, the rocker, the spocker,the shocker, the show stopper, and finally Ender's Game.
Nick "My woman said she wouldn't make me a sandwich"
Steve "What did you do?"
Nick, "I skipped from pleaser to Ender's Game, and lets just say, best fist bump ever!"