A [[tag group:sex acts|sex act]] in which just the head of the [[penis]] is stimulated without touching the shaft.

This often takes the form of a [[handjob]] where the palm is used to rub the head in circles, or a [[cloth glansjob]] where a taut piece of cloth is used to rub it back and forth. It can also be accomplished by performing fellatio on just the tip of the penis.
亀頭責め