In an effort to get more people to kiss them, scientists at the Netherlands Organization for Applied Scientific Research have released a series of research data that provides a solid reason for making out (besides leading to steamy sex): strengthening the immune system and fighting off disease. But not the zombie plague -- no amount of kissing is going to help you if you get bit. Same goes for getting vampired (picture related).
80 million bacteria are transferred during a 10-second lip lock. And in order to share similar salivary microbiota, partners should kiss at least nine times per day.
The idea is that if you and your partner make out regularly, you'll build similar cultures of oral bacteria and boost your immune system by making it cope with these bacteria in a relatively small dose (kind of similar to getting a vaccine). So get out there and start kissing! Just make sure to chew some gum first, because your breath does smell like you just ate a bag of shit.
Thanks to Thaylor H, who agrees that in addition to nine kisses, it's also important to get at least twelve hugs a day.