It's simple. Dressed as Captain Rulerman (in black tights, and a cape with a giant fluorescent tape measure embroidered up the back), I sneak up to the likes of Tom Cruise and politely ask them for an autograph, while a paparazzo colleague clicks away from behind, capturing photographic proof that the star in question is only 4ft 9in, and not 6ft 4in as claimed by his PR company.