what game did dill say they were playing

They werent playing a game when Jem lost his pants, they had written a letter and they were crawling under a fence to leave the letter on the Radleys back porch, But after they heard a noise in the house they ran away and Jems pants got stuck on the fence so they left the pants behind only to find them stitched up and on the ground when they went back for them, we can only assume Boo stitched them up.

Dill says that he won them in a game of strip poker.