Leonardo DiCaprio, Robert De Niro, Robert Downey Jr. Dine at Giorgio Baldi

Leonardo DiCaprio, Robert De Niro and Robert Downey Jr. walk into a restaurant … there’s no punch line here — ’cause it really happened Thursday night!

The three Oscar winners all hit up Giorgio Baldi — a fancy Italian spot in Santa Monica … with the Roberts enjoying a night out with their significant others and Leo rolling solo.

All three men dressed casually … nice jackets and T-shirts — nobody went full suit. De Niro and Downey were easily identifiable, not covering up at all — while Leo wore his usual hat and mask to avoid giving photogs a shot of his face.

We should note … we haven’t seen any pictures of them at the restaurant together — so we don’t know if they met for dinner or if this is just a star-studded coincidence.

De Niro and DiCaprio are longtime collaborators — first appearing onscreen together back in the 1993 movie “This Boy’s Life” when Leo was just 19. They also starred in the Oscar-winning flick “Killers of the Flower Moon” last year.

Downey, on the other hand, hasn’t worked with either of the men … though he collected his first-ever Oscar earlier this year for his role in “Oppenheimer.” He’s headed back to the Marvel Cinematic Universe — so unclear if he’d even have time to act alongside his fellow legends.