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1.
Mogag is the term to apply to any organic goop of unknown origin or composition, applied especially when referencing the body oils and filth that comes off pool and spa filters when they are cleaned.
Biff the poolman was totally grossed when he had to clean the jacuzzi filters at the hotel where a bunch of wanks and skanks had just had their convention. "Dude, the mogag was coming off by the bucketfull, and the smell was grotty as hell!"
by DaveDammit May 08, 2007
 
2.
Any funky, smelly stuff that while not readily identifiable is nonetheless of biological origin.
Dude, look at that mogag coming off those pool filters!

Or: I was about to shag your sister last night, but I when she pulled down her panties I caught a whiff of some incredibly nasty mogag.
by Dave What A Guy May 15, 2007