n. Abbreviative form of "Man Grown Up" The highest form of "Bullsh!t" or something that may anger someone, following "Faggotry". Either used as the whole term or as the abbreviative.
"Gee, Johhny! Were you in that meeting? It was pure faggotry!"
"No Earl, That was some straight up MGU...to the fullest."
"No Earl, That was some straight up MGU...to the fullest."
by Dballer1 February 10, 2010
Get the MGUmug.