Just sit there and smile mysteriously. Be prepared to move out out of the way quickly if either of the people on each side of you begins to have a potential projectile inclination.
Or go the the lavatory for 15 minutes. Time it carefully or the dessert may have come and gone or been eaten by someone else.
Drop your napkin and disappear when you are picking it up. Unless you really want the dessert, in which case, just sit there on the floor under the table. You might learn something interesting.