The act of stimulating another person's penis by vulva , but without vaginal penetration.
It mainly indicates that somebody is grinding or rubbing someone else's pussy(penis) to own penis(pussy).
Many thigh_sex and tribadism_on_penis contain this tag.
Not to be confused with penetration.

See also:

• frottage - penis + penis
• grinding_on_penis Where the stimulation is of the pussy.
• hot_dogging - phallus + buttocks (assjob)
• tribadism - pussy + pussy

• prodding