Aviva Drescher (left, the leg-thrower) and LuAnn de Lesseps. (Heidi Gutman/Bravo)

There are so many milestones for reality television. This is an especially noteworthy one.

On Tuesday night, one of the “Real Housewives of New York City’s” cast members threw her prosthetic leg across the room during fight at a party.

Let that sink in for a second.

Knowing what its viewers want out of the “Real Housewives” franchise, Bravo has been promoting this very special moment for weeks with preview clips, and obviously saved it for the season finale. It was meme-ified before the episode even aired.

Still, seeing it actually happen in context? Rather shocking.

The brief back-story, if you’re wondering how things got to this point: Cast member Aviva Drescher, the leg-thrower, caused some drama in the past when she

another “Housewife,” Carole Radizwill, of hiring a ghost writer for her book. Things got worse from there. According to E!, Aviva has been

most of this season.

She returned with a vengeance on Tuesday. The tipping point was at a party, when several other cast members accused Aviva of lying about and exaggerating the symptoms of her asthma, which she used as an excuse to skip a recent trip to Montana. That made Aviva furious and it sparked a lengthy, confusing, truly bizarre fight. Finally, it boiled over.

“The only thing that is artificial or fake about me — IS THIS,” Aviva roared during the scene at Le Cirque restaurant, as she detached her prosthetic leg and slammed it on the table. “I am sick of you all accusing me. Everything else is real! I’m sick of being called fake.”

Most everyone gaped in horror, gasped or screamed; one woman was laugh-crying too hard to breathe.

Aviva turned her furor to fellow cast member Heather Thomson. “Why don’t you take it? I’ll crawl home,” she demanded, hurling the leg across the room in Heather’s direction, and then lifting her glass for a toast.

Cue lots of shots of the leg lying on the floor as everyone stared at it; jaws literally dropped. Eventually, Carole — her nemesis — picked up the leg and returned it to Aviva.

So, over what apparently is a first for reality TV, Bravo seems proud — immediately after on “What What Happens Live,” it was all host Andy Cohen could talk about. Calling it the “leg drop heard ’round the world,” Cohen boasted that “New York Housewives” and #LegGate were trending worldwide on Twitter.

Joined by cast members “Countess” LuAnn de Lesseps, Ramona Singer and Heather, Cohen dissected the “leg-endary” incident over and over, as they cracked up re-watching the footage. Heather speculated that Aviva had been waiting for that moment for years; the others agreed that it was probably premeditated, especially since she was able to take off her leg so quickly.

And just so you know: Yes, Aviva has been allowed back to the super-fancy Le Cirque, even though leg-throwing is technically not great etiquette.

Anyway, Aviva didn’t seem too fazed by the incident. “I was being attacked by three shrews at cocktail party — some people throw down their glasses and I just threw down my leg,” Aviva explained after the fact on “Access Hollywood Live,” where she swore that it was a spur-of-the-moment reaction and that producers had no idea it was coming. “I had to make a point, so I made the point by throwing my leg on the table to shut them up. What else was I going to do?”

Aviva, whose leg was amputated after a farm accident when she was 6 years old, also gave more details on “Access Hollywood” about how it is, in fact, very easy to remove your artificial leg, especially if you’re sitting down. “I normally loosen it a little bit to keep the blood circulation going,” she explained. “I wiggle my leg and it’s very, very fast. You just press a button and loosen up the leg.”

The more you know, right? Aviva also threw one last zinger at Kristen Taekman, who whirled around in horror when the leg went flying: “I’m very disturbed on behalf of the whole amputee community that she was so repulsed by the sight of a prosthetic leg.”