Disclaimer- I don't own Harry Potter.
Severus Snape, dressed in a clean robe of lurid pink, purple, green, orange and blue, skipped down the hallway. The song he was singing was probably from a singer that didn't have a pristine reputation, judging by the lyrics they understood from his offkey yodelling, and he danced with any female who could stand in his presence. He held his afro covered head high, ignoring the people around him who were suddenly falling to the ground.
He passed the Headmaster, who was summoned by a student who managed to keep their head, but the headmaster was promptly flipped off and then watched as his deputy was kissed, and it was a deep back bending kiss too. He grabbed Gilderoy Lockheart and started dancing the tango down the hall, until Lockheart broke free, then he skipped off to another hall.
Severus giggled and through points around, ordering anyone that attempted to address him, to call him Sevvie.
For nearly an hour, they were subjected to this Severus Snape, who was considered scarier then anything seen naturally. And everyone saw it.
Poppy Pomphrey had never had such a fill Hospital wing, composed mainly of Hysterics.
Then he went into the dungeons and came back as he normally was. Though maybe a little bit more strict.
In a storage room in the dungeons, Harry grinned at what had happened, before he gifted Dobby with a set of wizarding robes.
Snape never recovered from this.
And neither did the school.