magoosh Share definition Flag When someone takes a fat shit on your bed after drinking Jack Daniels. "That dumb bitch was so drunk last night, she took a fat magoosh. Looks like laundry day for my bedsheets." magoosh by haverford720 March 13, 2014 0 0 Get merch Get the magoosh mug. Buy Now — $32.95 See more merch