During a windy day, Klee attached small firecrackers to her Jumpy Dumpties and floated them over the cathedral fountain. When Barbara tried to bless the water, the bombs went off, turning the holy water into a hot spring. The Result: Mondstadt got a free sauna. Barbara laughed it off, but she now keeps a Hydro shield up at all times.
To understand the "prank" aspect, you must first understand Klee’s disciplinary record. According to her profile, Klee has been "confined" by Jean (the Acting Grand Master) more times than any other knight in history. The charges? Fishing with explosives (blast fishing), leveling portions of Stormbearer Mountains, and creating "sunsettia-scented" bombs that caused the Cat's Tail tavern to smell like burning fruit for three weeks. Klee Prank Adventure
In the fandom, these aren't seen as crimes; they are seen as pranks. During a windy day, Klee attached small firecrackers
A Klee Prank Adventure usually involves three core types of pranks: Barbara laughed it off, but she now keeps
This is Klee’s signature move. While the rest of the world fishes with rods, Klee fishes with pyrotechnics. During her most famous prank adventure, she tossed a cluster of her custom bombs into Cider Lake, claiming it was to "help the fish fly." The Result: A geyser of water, stunned trout, and a very wet Diluc who happened to be walking by with his morning grape juice.