Stu & Pid are obstacles in SMG3's lair to prevent Mario and SMG4 from stopping him to upload a video containing content of SMG4's most weird and embarrassing moments. They debut in SM64 Bloopers: Smg3's gauntlet of gloom.
Stu and Pid are Piranha Plants who seem to be brothers, and as their combined name suggests, they are StuPid. They constantly fight over small things and call each other dumb which is in fact true, again relating to their combined name.
Stu is a yellow Piranha Plant with white polka-dots who is Pid's brother, Stu is the plant who is a liar, Pid likes to show off with saying stuff to make him "look tough" according to Stu.
Pid is a purple Piranha Plant with white polka-dots and is Stu's brother, pid tells the truth, whatever Pid does, he sometimes annoys Stu leading Stu to say that the stuff he does is dumb.
Mario and SMG4 enter a mysterious room with two doors leading to a room. Mario is about to approach a door when the two plants rise from the ground, and Pid demanding the friends to 'stop right there'. Pid threatens the pair by saying to Stu that they have 'fresh meat', Stu then accuses Pid of trying to 'look tough' and then Pid denies that being true. Then it causes an argument that distracts them for a moment. Mario attempts to run for a door then he is blocked just in time by Stu. Pid and Stu then urge Mario and SMG4 to solve their riddle, Pid then does an evil laugh which causes Stu to say that they already have agreed on no evil laughing which yet again causes another argument, Stu saying that evil laughing is 'dumb' and Pid saying that Stu is 'dumb'. The plants tell the Mario and SMG4 that one door leads to another room while another leads to their "ultimate doom". Pid then asks Stu if he can evil laugh again, which Stu replies with a sigh and then finally grants him permission only to do it 'just this once'. SMG4 then approaches Stu to ask what would Pid say about the door that leads to the room. Stu says that Pid would say it's the door on the right that leads you to the safe room, but SMG4 knows that it's the left door that leads you to the safe room, since Stu is the liar. Yet Mario does not understand how this works, so SMG4 attempts to explain the way Mario understands by using spaghetti, being Mario's favourite food. Mario still does not understand so SMG4 takes mario with him into the left door that is safe. Pid then says 'those guys were pretty nice' but then Stu says he is unsure about Mario being the "retarded one" and says that he reminds him of Pid, in which Pid replies about Stu 'wanting to have a go at him' causing ANOTHER argument until Bowser shows up. They then greet Bowser by calling him a "giant turtle" and tell him that he must solve their riddle. Bowser decides that he cannot be bothered doing so and burns the plants with his fire breath and heads the right door.
Stu and Pid are two of the many Piranha Plants that Peach burnt on fire in the garden. However, they are enjoying it.
- Pid and Stu are one of the few characters featuring voice acting instead of taking sound files from another source. The voice acters are SMG4 himself and his brother.