Definitions by Synovial_boy

m-u-ing 

pronounced Em-you-ing
Mutual Understanding
used to explain a romantic relationship where two partners are not going out, for whatever reason

Guy 1: hey, dude, is that girl you were with your girlfriend?
Guy 2: umm, no, we're kind of m-u-ing

m-u-ing by Synovial_boy September 16, 2008