Light-fingered pupils may be able to smuggle a bag of penny sweets up their jumpers, or even a family pack of Hula Hoops. But even the most ambitious would probably stop short of trying to squeeze an entire dinosaur up there.
We can only assume that Mexican thieves are more ambitious. They have managed to steal a #163;60,000 remote-controlled dinosaur robot from a Walking with Dinosaurs show in Guadalajara.
It's the first time an exhibit has been stolen from the show, which has toured worldwide and had more than 4 million visitors.
"Only in Mexico!" cried a surprisingly cheerful Karla Arroyo, a spokeswoman for the show.
The missing five foot robot is the least expensive in the ensemble. If the robbers had done their homework, they could have gone for one of the 42 feet dinosaurs, which are worth up to #163;600,000.