msls Share definition Flag Muff sucking lips, not to be confused with dick sucking lips or DSLs. Usually worn by men or manly-looking women, rarely glossy. That girl that was hitting me at the gay bar had some serious MSLs. msls by Bishywishy October 21, 2010 0 0 Get merch Get the msls mug. Buy Now — $32.95 See more merch