When it's overly warm/hot either indoors or outside. Sometimes brought on by wearing to many layers. Can even be used in hot tub/sauna like situations when you actually knew it would be hot before you went in. Sometimes like actually being trapped inside a giant muff
Guy1:"Fookin hell it's well muffy in here - can't you open a window?"
Guy2:"I did but its muffy outside too!"
Guy1:"I think i may die from the muffyness!"
"muffy" (or muffin top familiaris) as named by Sir Paul James on his recent trip to the anglo americas - A "muffy" is a woman of anglo persuasion who is clearly rotund and known for her "muffin top" accenting her already curvaceous body shape.
For those who enjoy a woman with a proper "muffin top" it is a delight to locate a genuine "MUFFY" in cosmopolitan areas as they are known to normally isolate themselves to their area of origin (Connecticut).
Hey, Tom I noticed your taste for Rubenesque women wearing J-brand jeans 2 sizes too small. I located a genuine Muffy (top and all) over at Norwood. I'm sure you will be busy sinking your teeth into that for days.