see WINDY CITY HEAT; the GREATEST tv show of this type premise EVER
on comedy central 10 yrs ago, was WINDY CITY HEAT, the funniest practical joke/movie, w/a similar premise to harry, etc., ever made
and yet, practically nobody has seen it, although it does have a strong cult following
basically, this loudmouth is convinced he's been cast in movie, and EVERYBODY else in the project is in on the joke, except him
get the dvd, it's unbelievably hilarious stuff; unique even within its genre
if you want a sample, go to youtube and search for windy city heat, red bat blue bat, or (another scene) perry knocks over the table
(and no, i have no connection to the movie; just a huge fan)