LMTO Share definition Flag The old english version of "LMAO", which means "laughing my tush off". Most commonly used in the early internet, and was replaced with LMAO. That's so funny, I'm LMTO LMTO by Sir_Platypus_VII November 28, 2023 0 0 Get merch Get the LMTO mug. Buy Now — $32.95 See more merch