Oral sex is the act of sexual intimacy from mouth-to-penis (fellatio), mouth-to-vagina (cunnilingus), or mouth–to–anus. Or in slang terms: a blowjob, going down, giving head, or rimming. You won’t get pregnant from oral sex, but you can infect an STI. Choosing whether or not to have oral sex is a personal decision. Some couples love it, but others do not. You …