This is more of a door prize than an actual game.
Fold small white napkins or squares of fabric into little diapers and fasten with a diaper pin. Place an opened candy kiss in one of them. Give them to guests as they arrive at the party. Warn them that one may be a dirty diaper and they'll get to change it when everybody has arrived. Have everyone open their diapers together at some point during the party and the one with the kiss wins a door prize.
