How do you define sex?

So just wondering how people define sex. I know people who define it only as intercourse, and I know of other people who define it as everything, oral, petting, playing...
Personally I think sex is anything with your partner that makes the two (or more) of you happy. A good night of sex is a 69 for me. Any additional activity is good too, but if not, I would still consider it sex.
Thoughts...??