50 Cent is going OFF on Hollywood producer and fiance of "Vanderpump Rules" star Lala Kent, Randall Emmett ... threatening physical violence if he doesn't pay him by Monday.
Fiddy fired things up on his Instagram Friday by mocking Lala over a 'Vanderpump' clip in which she admits Randall gifted her a Range Rover after the first time they had sex. 50 wrote ... "10 seconds left in the 4 quarter hoe's are Winning. Do you want A range rover, yes, **** yassss. Then just run out and suck a d-–k. LOL smh."
Lala - Fun - Thug - Bravo - Rapper
After Lala clapped back by making fun of 50 for claiming to be a thug but watching Bravo, the rapper decided to set his sights on Emmett ... who he apparently has MAJOR beef with.
50 began posting screenshots of texts with Randall -- a fellow executive producer on his show, "Power" -- calling him a loser and asking him if he told Lala he owes him a million...