Rob Reiner’s son Nick was ‘freaking everyone out’ and ‘acting crazy’ at Conan O’Brien’s holiday party before murders

Nick Reiner was reportedly acting erratically with guests at Conan O’Brien’s Christmas party Saturday night — hours before his parents, Rob Reiner and Michele Singer Reiner, were pronounced dead.

“Nick was freaking everyone out, acting crazy, kept asking people if they were famous,” an insider told People Monday, with a second source claiming to Us Weekly that he behaved “creepily” at the bash.

Several other insiders echoed previous reports that the 32-year-old then allegedly got into a “very loud argument” with Rob, which resulted in his parents leaving the party post-confrontation.

Reps for O’Brien and Rob did not immediately respond to Page Six’s requests for comment.

As Page Six previously reported, Rob and Michele were found stabbed to death in their Los Angeles home on Sunday afternoon. Sources told The Post that their 27-year-old daughter, Romy Reiner, discovered their bodies.

“It is with profound sorrow that we announce the tragic passing of Michele and Rob Reiner,” the family confirmed in a statement to Variety.

“We are heartbroken by this sudden loss, and we ask for privacy during this unbelievably difficult time.”

Early Monday, Page Six confirmed that Nick was arrested on charges of murder and is currently being held at Twin Towers Correctional Facility in Los Angeles without bail.

Nick has notoriously had a rocky relationship with his parents and has openly struggled with drug addiction. He also allegedly had a history of violence, according to sources who knew him and the family.

“This is not the first time their son has been violent,’’ a longtime neighbor of the Reiners, who asked to remain anonymous, told The Post Monday.

“I know of another incident a few years back with Nick, but I won’t say more than that. I just never thought it would ever get to this point.”

An insider also told us that the suspect “really resented his dad” and “hated himself for not being as talented, prolific or beloved.”

Meanwhile, Alanna Zabel — a yoga instructor who taught Rob and Michele — spoke to Page Six Monday about Nick’s “egocentric” behavior and “screaming” sessions that would allegedly last up to 20 minutes in the early 2000s.

She described Nick as “this little boy” with “behavioral issues” who was “trying to figure it out” but “always upsetting everyone.”

Rob, who was 78 years old, and Michele, who was 68 years old, also shared a 34-year-old son, Jake Reiner.

The actor also had an adopted daughter, Tracy, 61, from his first marriage to Penny Marshall.

Rob and Michele had been married since 1989.