Wow, what a really clumsy, ignorant, or foolish thing to do or say! (Ex-Lax is the brand name for a type of laxative, which helps promote bowel movements.) Primarily heard in US. Smooth move, Ex-Lax! Thanks to your insulting remarks, they've decided not to invest in the project! The plates all crashed to the floor as I slipped on the spilled wine, and someone in the corner of the restaurant shouted out, "Smooth move, Ex-Lax!"