For this example, we'll say the teams are boys vs. girls. Once everyone is done with their treat, the 'guessing team' is let back into the room. You could make it harder by starting out with only a 'lip kiss' and then guessing, then moving onto 'tongue kisses,' etc.
Couples can keep going until they guess right, or a limit can be set on guesses.
Between rounds, everyone should take a drink of water to clear their mouths and make sure everyone has an equal taste.