Practical jokers are using the internet to poke fun at troubled actor ROBERT DOWNEY JR.'s incarceration - by downloading what they claim is the diary of his first 20 days. According to the hilarious scribbled notes, the actor, who was jailed for three years in August (99) for parole violation on drugs and weapons charges, has found ALLAH and changed his name to MOHAMMED MOSIAH. The notes say he's determined to "show the gritty, seamy side of prison life" on the big screen upon his release. The phoney diary also notes the actor's disappointment at not sharing a cell with Charlie Sheen - "I thought he was going to be in here at the same time. " The memoirs include details of the number of times Downey Jr gets beaten up by fellow inmates, who take exception to the film roles he has played - "I got my a** kicked by my cellmate RAMON because I played a queer in One Night Stand (1997), and he hates queers."