Andy Cohen -- PRE-GAME SEX IS CRUCIAL ... 'Let the Poison Out'

Bravo's Andy Cohen is a HUUUUGE St. Louis Cardinals fan ... he even named his dog after a player ... and he's got some great advice for the team before their next playoff game -- GET LAID!!!

Andy was out in NYC Wednesday when we asked how he felt about pre-game sex ... since so many World Cup teams BANNED their players from banging during the tourney.

But Andy is all about it ... telling us, "They should burn it out, let the poison out!"