On Tuesday, Matthew was busted for theft . . . while wearing a full-body Cookie Monster onesie!. 

It would be perfect if he'd been busted for stealing cookies . . . but we're not THAT lucky.  He was stealing stuff from a construction site with a friend.


The friend was 23-year-old Dean Stevens, who had the good sense not to dress as a "Sesame Street" character.


But they were both arrested for theft. 


(ABC 13 - Houston