When a woman blocks another woman from a potential hookup with a guy. Usually involves unsubtle flirting. Oddly, women with boyfriends or husbands perpetrate the muff block and have no romantic interest in the guy, shutting down their available girlfriend. Female version of the cockblock
1) I think Maryanne is muff blocking Allie. She walked right over and starting rubbing his shoulders and stroking his hair while Allie was talking to him.
2) Carol did a classic muff block when she sat on Rob's lap right in front of Heather.