Super Mario 64 Bloopers: The Imposter is the forty-third episode of Season 2 and the ninety-second overall to be uploaded by SMG4.
This episode was aired on July 29, 2012.
The episode starts outside Peach's Castle one night. After sneaking past outdoor security, SMG3 heads to the castle dumpster and calls for somebody inside. The mysterious character is annoyed at being woken up. SMG3 asks his skills to take out SMG4 and his friends. The shadowy man accepts after receiving payment of one Justin Bieber magazine. The two villains start laughing until the shady man ridicules SMG3 for his laughing at an unfunny matter. SMG3 says sorry.
The next morning, MM54321 walks out of the castle remarking on the beautiful day. The stranger approaches him from behind and takes form of MM. The impostor quickly takes him out as MM looks behind him.
Mario says hello to a cranky Toad and exits the castle to find MM lying on the ground. After mourning, Mario decides to use mouth-to-mouth to save him. MM responds by stating he isn't dead, continuing to lie on the ground. Mario returns inside and the impostor, still disguised as MM, follows him. The impostor asks about SMG4's whereabouts, revealing he intends to assassinate him. Mario directs him to the castle's guest room.
Starman3 arrives and asks what MM is doing and Mario tells him about the assassination attempt on SMG4. Starman, shocked, stops the impostor from entering the guest room and the impostor heads into another room. Inside, he finds X, who offers him spaghetti. The impostor takes out X and takes form of him to keep his cover.
The impostor leaves and Mario walks in the room soon after. Horrified that perfectly good spaghetti was left on the ground. He takes it, says hi to X's unconscious body, and leaves.
The impostor approaches SMG4 and chases him through the castle. SMG4 tries to counterattack but fails. Before he is killed, SMG4 escapes the guest room he was cornered in and calls for Starman's help. Inside they find the impostor has taken the form of a nude Mario who starts to rickroll.
Starman gathers Mario, Luigi, and SMG4 to discuss whether there is an impostor among them. Mario believes it is Luigi and shoots him. Starman deduces that Luigi probably wasn't the impostor and Mario shrugs it off. Suddenly the impostor, disguised as Toad, transforms into his original form and tries to shoot Mario. Fortunately, the impostor is out of ammo and before our heroes can question him, he teleports away.
Our heroes begin a castle-wide search with: Starman searching the upper floor, Mario searching the ground floor, and a nervous SMG4 searching the basement. All SMG4 finds in the basement is a hobo. Mario attacks an old lady who he thinks is the impostor, only for Toad to tell him she isn't. Starman finds nothing except for Prinplup who he punches.
Finally SMG4 confronts the impostor in the castle basement. As the impostor prepares to end SMG4, Starman arrives and throws a sink at him. The impostor escapes into Lethal Lava Land and the trio chase after him, despite Mario's promise to play Super Smash Bros. with Toad. Toad is ready to play Super Smash Bros. with Mario, but realizes Mario isn't coming and is sad. The impostor races through Lethal Lava Land and has his location protected by the Big Bully. While Mario tries to make peace with the impostor, Starman defeats the seemingly invincible Big Bully. The impostor escapes into the volcano and the heroes give chase.
SMG4 goes and faces the impostor alone, attempting to talk it out. The impostor refuses peace and after a long fight, the impostor gains the upper hand. SMG4 pulls off the special attack he forgot he had and the impostor is defeated. As he tries to escape one last time, his platform gives away and the heroes watch as he is toasted by the lava. After being buried outside the castle, SMG3 visits his grave and regards how useless he really was.