Whispy blink glitch
The Whispy blink glitch is a glitch performed in Super Smash Bros. Melee. The glitch was first discovered by Magnus420 on SmashBoards.
The glitch was fixed in the PAL version of the game.
How to perform
The player must choose Marth or Roy in any type of Melee match or training and choose Dream Land as the stage. Then, wait until Whispy Wood blinks. On the last 2 frames of Whispy Wood blinking, the player must execute a jab, forward tilt, up tilt, down tilt, dash attack, or standing grab. Marth or Roy will swing their sword in a unusual way. The hitboxes for these attacks (sans standing grab) will disappear until the move finishes. As for the standing grab, Marth or Roy does the grab without lunging forward, making it safer than a normal grab. This method, however, is inconsistent, and there might be other undiscovered conditions this glitch works on.
Explanation
No one knows why the hitbox dissappears when Whispy blinks.
One explanation provided by Evsen on reddit on September 2016 stated that when he was using Dolphin emulator's texture dumping feature. He claimed that Marth's face was dumped on Whispy Woods. He assumed that Marth and Roy's blinking animation is tied to Whispy's, explaining why attack animation messes up, because the game is trying to use their blinking textures at the same time. This theory was proven false after four years by AsumSaus, who asked Evsen for the footage. When he played it again, he could not recreate the blinking textures again. AsumSaus stated, "...was most likely a mistake." With Evsen playing as Marth or choosing Marth as the second character, seeing Marth's blinking textures being dumped and later misremembering."
To this day, the reason behind this glitch is still unknown.