Jack Osbourne Reunites with Alleged Car Slasher

6/15/2010 4:10 AM PDT

Jack Osbourne Reunites with Alleged Car Slasher

Jack Osbourne hugged it out with his ex-GF yesterday in L.A. -- the same girl who allegedly keyed a nasty message into the roof of his $250,000 car ... and TMZ has finally learned what that message was.

According to sources, 24-year-old Niki Cloyd carved up his Aston Martin with a certain four-letter word ... beginning with a "D" and ending with a "K" -- causing at least $10,000 in damage.

By the looks of the above photo, Jack seems to be over the spat -- so it's a good thing Osbourne never got that restraining order he requested.

But the L.A. District Attorney doesn't forgive so easily -- because Cloyd was officially charged with felony vandalism yesterday .... and faces up to three years in prison if convicted.