Bare-skin rubbing

Full body rubbing with skin-on-skin contact, sometimes called dry humping if genitals aren’t directly involved. For example, sliding your body against theirs while both nude (or underwear only). Feeling all the skin friction and warmth can be extremely erotic even without penetration. This can include rubbing genitals against each other externally (e.g. rubbing a penis along the vulva without entry).