1) To be completely and hopelessly loaded down with work. Can be used in the same way as " In the weeds" would be used in a restaurant setting.
2) a girl with huge, overgrown pubic hair.
1) Lambchop: Meaty, can you take table 10?
Meaty: No fucking way! Im in the full blown muff over here! Steph just triple sat me and Charlie is putting out food way to fast.
2) David: Are you gonna hook up with that hippie chick?
Sherman: I was going to but I could see by the way her bikini was all puffed out she had full blown muff and I just can't get down with that.