noun
sexual intercourse; actual sex
Slang term, often used in contexts distinguishing real sexual activity from simulated or non-penetrative acts, especially in the sex industry or adult films.
See also: 本番 (ほんばん)
風俗店では本番行為は禁止されている。
Sexual intercourse is prohibited at this type of sex establishment.
そのAV女優は本番行為をしないことで知られている。
That adult video actress is known for not performing actual sex.