The yo-yo stack glitch is a glitch in Super Smash Bros. Melee that results in Ness having several of his down smash yo-yos visible at once. By using a down smash on the earliest interruptible frame of a previous down smash (frame 59), the old yo-yo is retained instead of disappearing, following one frame behind the new yo-yo. The process can be repeated indefinitely to stack further yo-yos, resulting in a kaleidoscoping effect due to the intersecting polygons. Interrupting the down smash on a slightly later frame, or interrupting with an up smash instead, will keep the current number of duplicated yo-yos but not add another. The glitch ends naturally once the chain of interrupted up or down smashes does, and it has no effect on the move's hitboxes.