After cross-dressing for new “Sherlock Holmes” movie, ROBERT DOWNEY Jr. plans to film a remake of the clas­sic gender-bending comedy “Some Like It Hot”!

Downey has even recruited British heartthrob JUDE LAW, his co-star in the upcoming sequel “Sherlock Holmes: A Game of Shadows,” to join him in the drag extravaganza, insiders say.

“Robert was so excited about his ‘Some Like It Hot’ moment in the new ‘Holmes’ movie that he’d dance and twirl around the set in a dress and makeup for the cast and crew,” a source on the film divulged.

And Law, 38, who plays Holmes’ re­sourceful sidekick Dr. Watson, “got into the act when the duo dressed up as nuns for another scene,” said the source.

In a key “Holmes” scene, 46-year-old Downey plays the “Some Like It Hot” card when he dresses as a woman in full makeup while hatching a caper on a train chugging across Europe.

The original 1959 comedy starred Tony Curtis and Jack Lemmon as two musicians who wit­ness a mob hit, and then flee town dressed in drag as members of an all-female band that includes Marilyn Monroe.

“Now Robert is set to take Tony Curtis’ role of Joe, and Jude will have Jerry, Jack Lemmon’s part,” the source revealed. “They’re looking for the perfect actress to cast as the all-girl band’s lead vocalist Sugar Kane, who was played by Marilyn Monroe.”

The on-screen duo have asked “Holmes” director Guy Ritchie to helm the “Hot” re­make, the source said.

“The guys had such a blast with the whole ‘Some Like It Hot’ idea,” said the source. “It inspired some of the best moments in the new ‘Holmes’ film.”