This just came to me one day.
Disclaimer: Harry Potter not mine

Salazar Slytherin walked into the newly built Hogwarts to get out of the pouring rain. He quickly cast drying charms on himself and headed toward his waiting dinner. As he entered the Great Hall, he heard his dearest friend the great idiot Goderic Gryffindor say "Hmm. The ceiling in here looks a little bare. I know!"

Salazar didn't hear the incantation his friend had used, but the results were immediately obvious. For the second time that day, he became soaking wet.

"Goderic you idiot! What in Merlin's great name were you trying to do?" Slytherin yelled. Drying charms would now be useless, as the rain that had previously been pouring outside was now pouring down on the Great Hall.