We have previously reported cases of dim-witted pupils committing this mistake: they film themselves vandalising school property, upload the footage on to YouTube and are then amazed at being caught. Some have even put their names on the credits.
Now, a headteacher in the United States has put a video on the internet to help nab a pair of vandals.
Two teenagers had used a basketball to knock out a CCTV camera at Sunset Elementary in Utah so they could break into a portable classroom. But a second camera had recorded their every move.
Don Beatty, the school's principal, edited the video and posted it on YouTube with a $50 (pound;25) reward for information. A few days later, he got a tip-off. The boys have since been charged with criminal mischief.
As for stupidity? Guilty as charged.