To masturbate simultaneously with at least one other person. Process includes group masturbation and mutual masturbation, but does not have to be either. Requirement is that more than one person must be involved in the masturbatory process.

Typically concludes with orgasm and/or ejaculation. Foreplay, which preludes additional sexual activities beyond masturbation, is generally not considered to be comasturbatory.

A casual invitation / threat used by an individual that is not afraid of fucking someone up.