'Lingerie' Football League -- Coach 'Under Review' for Locker Room Rant

A pro football coach is under fire for a locker room tirade in which he asked the players if they were "f**king retarded" ... but it didn't go down in the NFL -- it happened in a female football league.

TMZ has learned ... the Legends Football League (formerly known as the Lingerie Football League) is investigating Seattle Mist head coach Chris Michaelson for an angry expletive-filled halftime speech delivered during last week's matchup with the Green Bay Chill.

During the rant, Michaelson went full Rutgers on this team -- blasting his players for giving up a last-second TD before the half -- screaming, "Are you guys just f**king retarded???"

A rep for the league tells TMZ the matter is under review by the commissioner’s office ... explaining, "Everything is in line as far as what is expected from a football locker room, but we don't condone the use of the word retarded.”