Professor [Flitwick] was having a terrible morning, and it wasn't even breakfast yet. Someone broke into the [Transfiguration] classroom the night before, hid a Boggart in the closet, and set loose  doxies. How did he know there were 311 doxies? Because each one took a bite out of his [elbow] as he tried to capture it, and Madame Pomfrey had to [run] each wound separately. And comment annoyingly about how Professor [Sprout] would've had the room cleared out with 2 waves of a wand.
It took forever to get out of the infirmary, and by then Professor [Flitwick] was in a foul mood. Luckily, he knew how to improve it: by finding the culprits and making him, her or them pay. [Flitwick] had overheard some students giggling in the hallways the other day about [Cassandra Grubbly-Plank]'s stash of doxy eggs, so he had a good idea of who to interrogate first. Unfortunately for him, but rather fortunately for [Cassandra], the common room password had recently been changed to [Chuddley Cannons], so [Fliltwick] couldn't enter. [Sir Cadogan] looked up from (his) portrait and laughed at the cursing, frustrated Professor.
The old Professor [Flitwick] would have thrown a hissy fit at being taunted by a mere portrait, and blasted the thing all the way into the rd floor girl's bathroom. The new Professor [Flitwick] went to  weeks of Anger Management classes, punched a lot of pillows, and took up [weaving]. And started subscribing to the Weasley's Wizarding Wheezes catalogue.
Professor [Flitwick]'s first class off the day was [Transfiguration] with the 3rd year Hufflepuffs and [Ravenclaws]. It took them 2 hours to clean up after the entire carton of [Decoy Detonators] that went off and clung to their robes, schoolbooks, and any exposed flesh. The students all knew that [Cassandra] was planning to do something in [Transfiguration] to get Professor [Flitwick], so everyone blamed (her) for the prank and gave (her) the cold shoulder for 17 days, until [Stuart Cauldwell] blew up the [Divination] classroom with a misplaced charm and became the new pariah-of-the-hour.