Wachu Dern Share definition Flag slang term for what are you doing, mainly used by mtown hoodrats. Wachu Dern Niggah?Yo D-Smit Wachu Dern tonight? Wachu Dern by Dat Niggah Albe February 24, 2010 0 0 Get merch Get the Wachu Dern mug. Buy Now — $32.95 See more merch