BTuday Share definition Flag February 10; Commemorative day marking the birth of the Queen of sass and throwing phones at walls. Guy: Dude what's with the parade full of drunk people?Girl: Oh it's the BTuday celebrations in full send. BTuday by SamSepi01 February 10, 2020 0 0 Get merch Get the BTuday mug. Buy Now — $32.95 See more merch