Wumbly Woo means: One thing Markiplier will say every now and then, but it is the most memorable part of his 2017 video “I LITERALLY TROW MY CHAIRIN RAGE Getting Over IT – Part 1”. In which Markiplier attempts to figure out the type of hammer that is displayed on the title screen. In a FNAF4 Let’s Play, he also said “Wumpus Woo”, which I’m too lazy to look for. (in Community Dictionary, added by Lamar Tanner)