Tic Tac Toe
Draw a grid. Decide who will be X's and who will be O's. Then see who can be the first to get three in a row.
Take it outside, and make your grid on the driveway or sidewalk with chalk. Or take it even further: Make the grid out of sticks, and use different colored wood chips for the Xs and Os. markers. Use the chalk to mark the chips and to decorate the grid sticks.