When Gilderoy Lockhart used this incantation in his first second year Defence Against the Dark Arts class in September of 1992, it did absolutely nothing, with a pixie seizing his wand and tossing it out of a window right after. Whether it was due to the incantation being something Lockhart improvised on the spot or his lack of experience was the cause of the lack of effects is unknown.
Lockhart's use of this fabricated spell was apparently well-known, as a question on the 1996 Theory of Charms O.W.L. asked whether Peskipiksi Pesternomi was a genuine charm or not, and required the student to come up with a valid incantation that would have the actual desired effect.
It had absolutely no effect whatsoever on the pixies Professor Lockhart had released to fly wild throughout the classroom, resulting in Lockhart fleeing and leaving Harry Potter, Ronald Weasley and Hermione Granger to "nip the rest back in their cages." It is probable that this spell could not be effective in any case, as Lockhart had presumably invented it in that same class, with no forewarning and no indication that it would be successful.
Behind the scenes
- In the film adaptation of Harry Potter and the Chamber of Secrets, a pixie snatches away Lockhart's wand as he has barely finished the incantation of Peskipiksi Pesternomi. Due to this, some of the film viewers assumed the spell failed because of Lockhart's inability to keep his wand and complete the gesture, rather than because the spell itself did not exist.
- Harry Potter and the Chamber of Secrets (First appearance)
- Harry Potter and the Chamber of Secrets (film)
- Harry Potter and the Chamber of Secrets (video game) (GBC version)
- Harry Potter and the Order of the Phoenix (film) (Mentioned only)
- LEGO Harry Potter: Years 1-4
- Pottermore (Mentioned only)