You can not get pregnant by making out and rolling around on the floor.
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Kissing can cause numerous health problems – the common cold, chapped lips, swine flu, herpes – but there is no way that it can put a bun in your oven. The only buns that get in your body via your mouth are the ones that you chew and swallow.
As for rolling around on the floor… unless that’s a euphemism for “having sex,” you should be fine. Just watch out for splinters and stray penises that are trying to penetrate your inner fortress (by which I mean your vagina.)
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Explanation for why you can not get pregnant from a really hot make out session:
Making out may be sexual, it may even be “sex” by some people’s definition, but it does not cause sperm to get anywhere near an egg.