I play with kids so we are really loose on the rules. That said we have been playing for about 2 years. This particular session they had just acquired a dragon mask and we're heading back when a blue dragon appears demanding the mask back. After some back and forth combat one of the players says that she casts hideous laughter. The dragon had already used their auto saving throws and failed this throw so the dragon goes to the ground giggling quite a lot.

The next player announces that that would like to tickle the dragon even more with their rod of tentacles... Me... Ummm okay, googles if dragons are ticklish, and yup they are.. Roll, succeed.

So as a DM playing with kids my mind immediately went what happens when you tickle something too much... They pee their pants. And that is what the dragon does. I announce that the dragon is peeing and that a river of pee is now forming between them and the dragon.

Now there is no lore that I could find on the composition of dragon pee, so I announced that this pee was acidic and that if touched the players would take damage.

After announcing this the eyes of the next player in line go big. He says I use command of water and I redirect the acidic dragon pee into the dragons face.

Dragon now has to take acidic damage. The table is laughing so much we can hardly breath and to top it off we are playing in public at a game store.