Yakyuken (野球拳) is a Japanese variation of rock-paper-scissors wherein the loser of each round removes an article of clothing. Yakyuken gets its name from a Shinboku chant associated with the non-adult version of the game. It became a part of porn culture in Japan, and other Asian countries after the influence of TV variety shows and Soft On Demand. Numerous Hentai games have been made featuring the Yakyuken gameplay, and several American studios, such as Lost Bets Productions, focus on the filming and marketing of Yakyuken and other related strip games.
- edepot (2013-04-09). "First Adult Video Game: Yakyuken (ハドソン 野球拳 1981)". YouTube. Retrieved 2013-04-26.