SMG4's one of the YouTubers, SMG4Verse's Mario, Luigi, Peach and her castle are from Nintendo's Mario and this screenshot's taken from Valve's Garry's Mod.

Mario just turned himself into a ghost and just spooked Luigi while he was enjoying his fun with spaghetti, making him pass away temporary and turn him into a ghost as well. Peach freaks out and runs way while SMG4 was very annoyed with Mario's latest prank and is like "Really, Mario?" Gotta love how funny and crazy SMG4Verse can be.