Carlton's week from hell continues, with the AFL sending them a please explain letter over alleged umpire abuse by some fans.
News of the league's displeasure comes as Blues veteran Dale Thomas was fined a hefty $7500 at Tuesday's tribunal after pleading guilty to umpire abuse.
The AFL is looking into a claim that members of the Carlton cheer squad chanted "umpire, you're a wanker" during the narrow round-eight loss to Collingwood.
The league apparently is also unhappy that a drum was used in the cheer squad during play, which is not allowed.
Carlton have had a dreadful few days, starting with Sunday's 93-point belting from GWS that renewed scrutiny of their coach Brendon Bolton.
Veteran Marc Murphy suffered broken ribs in a heavy collision during the game and was sent to hospital, but returned to Melbourne the following game and will be out for several weeks.
Then Thomas found himself in hot water for his expletive-laden rant at boundary umpire Michael Barlow during the Giants game.