I like Sirius. I can't bash him, so I'll just have to humiliate him! YAYAYAYAYAY!
Sirius loped through Hogsmead in his dog form. He was extremely bored.
Suddenly, a little girl spotted him and shrieked in excitement. "MUMMY! Look! A dog! Can I take him home and dress him up and everything? Please?"
Padfoot recoiled and started running for it when he heard the mother say, "If you want, dear. Accio black dog!"
The big black dog whined piteously as he was dragged back to the little girl. She screeched happily and started plaiting locks of Sirius' thick hair together, tying them with little golden ribbons.
He was taken to a little out-of-the-way house, near a small patch of forest. Sirius was forced to have a long, soapy bath and several doggy makeovers. Half of his fur was red and the other half was a grey-ish black, with irregular patches of black.
Finally, the little girl got bored and went inside her house for the night. Sirius waited until all was quiet before he chewed the ribbons that held him through and made a run for it.
When he finally got back to Hogwarts, he entered the boy's dorm as a dog. Sitting on their beds were three grinning boys. James stood up and said, "Well hello, Padfoot, old chap! Had a fine time playing dress up?"
Sirius' jaw dropped as he turned back into a human. "You… you knew all this time?"
Remus nodded smugly and added, "Oh, by the way, you look like a candy-cane."
Peter piped up, "An evil candy-cane!"
His whole body was striped black and red. The three Marauders rolled around on the beds and the floor, laughing. Sirius glowering at them and storming into the bathroom simply sent them into hysterics.