transitive. To practise fellatio or cunnilingus on or with (a person). Also intransitive.

intransitive. slang (originally U.S.). To perform oral sex (on a person).

transitive and intransitive. slang. To practise fellatio or cunnilingus (on).

transitive. slang. To perform fellatio or (less commonly) cunnilingus upon (a person). Also with genitals as object. Also with off. Also intransitive.

To practise fellatio (or cunnilingus). coarse slang.

transitive. slang. To practise fellatio or cunnilingus on. Also occasionally intransitive.

slang. to sit on a person's face: to sit, kneel, or squat over a sexual partner's mouth, in order to receive cunnilingus, anilingus, or fellatio.