Spin the Bottle
Spin the bottle is the classic romantic kissing game, and few people reach adulthood without trying it at least once as a young teen. It can almost be considered a modern rite of passage. All you need is a bottle, a closet and a horde of giggling non-participants. Sit on the floor with a boy-girl-boy-girl arrangement. Put the bottle in the middle and pick a person to go first. The spinner gives the bottle a good spin and whomever the bottle lands on (nearest preferred sex) gets a romantic trip to the closet for "seven minutes in heaven" while the waiting horde giggles and gossips. Turn off the lights and use a flashlight instead of a bottle to add a little extra drama. A requirement of bright red lipstick on one of the participants can add to the giggles.
Send all the guys to one side of the room and all the girls to the other side. Blindfold each girl. Each guy in turn picks any girl and kisses her without revealing his identity. After each guy kisses a girl, and all the girls have been kissed once, the guys retreat to the other side of the room. The girls remove the blindfolds and make one guess about which guy kissed them. Guys hold their responses to right or wrong answers until each girl has made a guess. If a girl guesses the right guy, he's out. The game continues until only one guy is left standing.
Suck and Blow
Suck and blow is a game of skill and "accidental" kissing. Gather everybody in a boy-girl-boy-girl circle and give the first person a playing card. Business cards also work well in a pinch. The starting person sucks the card to her lips and turns to the person on her right, who takes the card by sucking as she blows to release the card. The timing has to be just right, otherwise the card will fall, resulting in a kiss. Any pair that drops a card is out and must leave the circle. The game continues until only one couple is left.