Unclear; probably "Pigley Dudley"
Endows pig-like features
- "He brought the umbrella swishing down through the air to point at Dudley — there was a flash of violet light, a sound like a firecracker, a sharp squeal, and the next second, Dudley was dancing on the spot with his hands clasped over his fat bottom, howling in pain. When he turned his back on them, Harry saw a curly pig's tail poking through a hole in his trousers."
Behind the scenes
- This spell is probably related to Human to pig.
- This spell is very specialised, acting only on one person and so it is likely that the incantation is "Pigley X", with X being the name of the target (so one might be able to modify it to be "Pigley Crabbe", for instance).