"Fuku wa uchi" is shouted because the temple enshrines Kishimojin (a goddess of childbirth and children, which term includes a Chinese kanji character of oni) in its precinct, and professional wrestlers enter the service for the shrine because it has kept the grave of Rikidozan, the late popular Japanese professional wrestler.
-境内に鬼子母神を祀るので「福は内」、力道山の墓所があるためプロレスラーが出仕する