smisland Share definition Flag this is when someone has armpit sweat REAL bad. They have it all the time, and it's real nasty. PRONOUNCED: smi-land T: are you smisland? B: no. T(whispers to K): ewwww, look at her armpit sweat. smisland by bulletproof! May 1, 2010 0 0 Get merch Get the smisland mug. Buy Now — $32.95 See more merch