I don't own Harry Potter.
James Potter, Sirius Black, Remus Lupin and Peter Pettigrew were all back at Hogwarts School of Witchcraft and Wizardry. And they were bored.
"Jamie, I want to do something." Sirius whined.
"Well go do your homework. McGonagall did set a two foot essay on the Fera Verto charm. And didn't I tell you not to call me Jamie. That's my cousin's name and my cousin is a girl.'
Sirius and the other ignored his rant. "I already have it done. Because of Remus, we all have our homework done. Now I bored."
"We're all bored. Why can't we all go and prank someone? We have all those plans from this summer. We haven't done a single one of them." Peter looked at the others hopefully.
"We can't. Mum confiscated them before we left for school. It's like she doesn't trust us." James gave an exaggerated sigh. "I always thought she respected my privacy."
"Well, she didn't look in my trunk. I think we put the majority of our rough drafts in there." Remus ran up to their dorm and came down with a satchel full of parchment. "It's all here. I didn't have the time to organize any of it."
Peter pulled out the top parchment. "Gentlemen, I think I may have found a winner." The top of the parchment read 'Operation Shampoo'. Peter was right it was perfect.
"Pete, you are the best of us at sneaking around unnoticed. What you need to do is find Snivellus and report back to us were he is." Sirius was bursting with excitement like an over grown puppy.
It took Peter twenty minutes to find Snape in the dungeon. He was brewing a potion that suspiciously looked like Veritaserum.
The four of them snuck down to the dungeon under James' invisibility cloak. He was glad his father sent it in the post because his mother would have taken that as well.
James and Sirius shot water at Snape. This effectively soaked him. Next Peter and Remus shot a shampoo charm at him. Then James did a spell that conjured a brush and it attacked Snape's hair. The boys were happy that Remus was an expert in charms and already knew the silencing charm because they were laughing so hard. They all cast another water spell at Snape. They all gasped.
Under all that grease, Severus Snape's hair was a light brown. The four boys stared at the fifth in an awed amazement. They had no idea that Snape had brown hair. They all left in silence (not that they had a choice).
When they reached the Common Room, Remus took off the charm. They all said the same thing.
"Wow. I had no idea that Snivellus had brown hair." They then all bursted out laughing.
The next day Snape was scene in the hall with his hat covering most of his hair. He had a very grumpy look on his face. Whether it was because of his hair or the ruined potion, no one ever found out. Peter said it might have been both.