Change showers water temperature

You decide that the best prank is change showers water temperature. The plan is: change gradually the water temperature from hot to extremely cold. This change will make their shrink to a small state. Then, you will stole them their clothes, forcing them to come out of the showers naked. And there you will be waiting with the girls just exposing her naked body and small dicks to girls eyes.

You plan goes well: They react late to the water change, so their dicks shrink a lot, and when they come out to get dressed, their clothes are missing. So they have to come out naked and then they all found themselves rounded by laughing girls, that took tons of pics of boys naked bodies, especially of their now small cocks, since the flashes of the cellphones makes them cover their eyes, exposing their small genitals.