|"I have absolutely no idea what's going on."|
F.L.U.D.D., short for Flash Liquidizer Ultra Dousing Device, is a minor character in the SMG4 series.
He is the device used by Mario to clean up Isle Delfino in Super Mario Sunshine and the device for Mario's down special move in Super Smash Bros. Brawl, Super Smash Bros for Nintendo 3DS / Wii U, and Super Smash Bros. Ultimate. It is capable of shooting water, but needs to be manually refilled. In SMG4's videos, it appears in SMG4: Stupid Mario Sunshine, which, of course, is a parody of that game. He was horrified by Mario's actions when he attempted to help others and ended up throwing Isle Delfino into chaos.
In the original game, Mario is tasked into using F.L.U.D.D in order to clean up Delfino Plaza and defeat several bosses. It is assumed that Professor E. Gadd left it for Mario to use, although this remains unknown as E. Gadd never made an appearance in the game. In the blooper, Mario actually stole F.L.U.D.D from Professor E. Gadd. When he requested Mario return it, he simply squirted him away. Presumably he returned it after the events of the video.