The other day we read "The Boy Who Cried Wolf" as part of a reading packet. I told my kids my own version of the story -- The Kid Who Cried Bathroom.
For some reason, whenever my students ask if they can use the bathroom, they feel the need to accompany the request with an exaggerated version of the Pee Pee Dance. Like if I don't say yes, the room is going to suddenly be flooded. So far, that's never happened. Well, if you don't count the kid last year who crapped in his pants. Or the kid they year before who told me "My bowels be runnin!'"
Usually, I tell the kid that they can choose to use the bathroom, but miss 5 minutes of recess OR they can hold it until our regularly scheduled break. Almost always, this little choice seems to soothe their bladder enough so they can resume their classwork with ease.
Now I just need to deal with the kid who still screams WOLF!! while IN the bathroom. . .