A film fan was left looking a little silly after he tried to “mansplain” Indiana Jones’s costume… to the woman who designed it.

Costume designer Deborah Landis’s son Max Landis shared a screengrab on Twitter of a Facebook conversation about a question on a television quiz show.

He wrote: “HOLY F****** SHIT dude online tries to mainsplain (sic) the costumes of Indiana Jones to my mom, the costume designer of Indiana Jones.”

The question was: “Charlton Heston’s wardrobe in 1954’s Secret Of The Incas inspired the clothes worn by this adventurous character 27 years later.”

The film fan piped up: “The Jeopardy question is wrong. The movie was The Greatest Show On Earth.”

But Max’s mother – a costume designer on the first Indiana film, 1981’s Raiders Of The Lost Ark – replied: “No. The question was exactly right because I provided it.

“Raiders of the Lost Ark is almost frame for frame Secret of the Incas.

“Heston later wore the same gear in Greatest Show. But his adventurer/treasure seeker Harry Steele cane first.”

Undeterred, the person responded: “Greatest Show came out in 1952, Incas came out in 1954.

“Spielberg acknowledges he was inspired by Greatest Show in numerous in interviews.”

Deborah replied: “Really, ‘In Interviews?’ I was there. He and I watched Incas together in an empty theater.

“Stanley, you have got to be kidding.”

Max’s Twitter followers saw the funny side of the exchange.

One said: “You win for best cringe-worthy mansplaining of 2017. Best to your Mom. (Who may be still shaking her head!).”

“That is the most epic mansplaining in the history of mansplaining!” tweeted another.