Frotting

[Tina]

Rubbing ones crotch against unexpecting people, furniture or walls. A favourite of sex-starved Japanese businessmen on the sub-way.

[Mark Zuckerberg]

When two men rub penises together in an attempt to start fire.

[Sonia]

Dry humping

[Sarah]

Sexually rubbing; the uninvited act of stroking ones cock on an unexpected pedestrian, or inanimate object.

[Becky]

The act of collecting faeces, menstrual juices and semen in ones mouth. There are many variations of how this is done but the original is as follows:
The male performs cunnilingus on the female, collecting the faeces and menstrual juice in his mouth. The female then offers him fellatio and through the process of snowballing, passes the semen into his own mouth.
Whether the frott cocktail is swallowed or spat out, is up to the discretion of the participants.