Private message to Padma Patil

Did you hear what happened to Diggory? It's hilarious. Someone hexed him, I guess, or maybe slipped him a potion? and now his pee is the most amazing shade of violet.

Someone saw, in the loo. Diggory seemed ... more than a little disturbed, I guess? Anyway he's off to Madam Pomfrey (although it's not like he was HURTING, I guess. Just very purple).

I wonder who pulled off that prank? I'd normally suspect the Weasley twins but I don't think they'd target Diggory.