Gigi-Does-It-Trae-Patton-IFCThe oddest performance of the fall TV season might come from David Krumholtz, who you know as the bright young man in the series “Numb3rs.”

Starting tonight, he stars, completely unrecognizably, as a 76 year old woman in the comedy “Gigi Does It” (IFC, 10:30 p.m.). In the role, where he does Caitlyn Jenner one better by jumping decades in age as well as gender, he futzes and does inappropriate things and seems to be pranking people in the manner of Johnny Knoxville in “Bad Grandpa,” whose prosthetic makeup people were also involved in the transformation.

Much of his interaction with a hired helper — co-producer Ricky Mabe — is more scripted, though.

It was Mabe’s idea of casting a grandmother in the first place.

“I created this weather-based website where an old, Jewish grandmother tells you the weather,” he told reporters at the TV Critics Association summer press tour. “We were originally going to cast an old, Jewish women to play the part, but after we wrote the scripts for that website, we felt really bad making anyone over 60 say those words.

“Dave and I have been friends for a over a decade, and I called him, and I was, like, ‘Would you be willing to play a grandpa a grandma?'” Mabe said.  “And on the phone, he literally broke into this character that’s based on his grandmother, and it was for 20 minutes. He didn’t shut up as this old woman. And then we ended up getting a great deal on the makeup, so we transformed him into Gigi.”

” I asked for a couple of prosthetic pieces, maybe a chin and a nose,” Krumholtz said. “And before you know it, my whole face, every centimeter of my face, my eyelids, everything, is covered in prosthetic makeup.”

“It takes me 4 1/2 hours. It’s a pretty lengthy and meticulous process,” Krumholtz said of the makeup. “If you are doing a beast or some sort of alien, it’s a lot easier to make mistakes, to smudge the corners; but when you are doing old age makeup and portions of our show are reality based, so I really have to convince people that I’m her. When you are doing that, it just takes a lot longer to get it perfect.”

Odder still is his internal transformation, based somewhat of what he remembers of his own grandmother.

“My grandmother passed away a little bit too young, and she was she would make Gigi blush. I mean, she was she was quite the spirit,” Krumholtz said. “And when the makeup finally came together and I put the wig on, what surprised me was that I looked a lot like her, that she was back in a weird way. And I hadn’t seen her since she passed. And so my first reaction was to get a little teary-eyed he was there because it was just overwhelming. And, then, you know, really, the character is an homage to her. I kind of channel something, and it might be her.”

I asked where they will take Gigi on the series.

“The show is about a woman coming into a great deal of money and money that she’s never had and  essentially her new lease on life, making up for lost time,” he said. “The first season is essentially about her searching for love, not just from, you know, a companion, but from the things that remind her of her youth.

“She wants to fall back in love with those experiences. So and also find love for herself. In fact, one of our episodes is about her posing nude in an art class to get over her body image issues.

“We went to a real art class with real art students and sat there and got sketched. That was fun. She revisits her passion for ice skating and finds out that Ricky is an amazing Canadian ice skater. There’s an episode where she accidentally discovers Internet porn. And she wants to get back into the dating world, the sex world, and she realizes that the requirements of what she needs to do sexually have changed, and she wants to brush up on the modern world of sex. So she goes and tries to figure out what positions she can get into and ends up hurting herself.”

But it’s not all so bawdy.

“There’s an episode simply where she wants her nine year old grandson to call her back,” Krumholtz said. “He’s got a cell phone, which she thinks is preposterous, and he won’t call her back. And so she goes to some ridiculous lengths just to get him to call her back.”