When you see something so orgasmic (Either sexual or just merely exciting to the senses, i.e. new footage of the next Star Wars movie), that you orgasm before you would have normally wanted to. Coined by the Game Grumps.
Pre-dating is the period of time before a couple becomes official. It often includes a significant amount of hanging out, flirting, and often times arouses suspicion amongst friends of either or both parties. Also see talking.
Friend #1: You and John have beenhanging out alot lately, are you guys dating???
Friend #2: No, we're pre-dating.