My son has outgrown Tic-Tac-Toe (although I shouldn't speak to soon.) He has however discovered Rock, Paper, Scissors which is far more action-packed. But, being a boy, he developed his own version: Tongue, Toilet, Booger. Don't ask.*
My son, for some reason, prefers scissors and almost never uses paper at all. This is his secret vulnerability (his Kryptonite if you will). So if you find yourself in a rock, paper, scissors marathon with him play for money and take him for everything he is worth. Just cut me in for a slice.
* OK, you asked - tongue is grossed out by toilet, which in turn is clogged by booger, which is licked by tongue. I told you not to ask.