Here are a few ideas, all TOS-era, of course:
1: Take an outdoor scene of John Wayne from one of his cowboy movies, but Photoshop him into a Starfleet uniform at Vasquez Rocks, armed with a phaser.
2: Jerry Orbach (Lennie Briscoe from "Law & Order") in a Starfleet admiral's uniform.
3: S. Epetha Merkerson (Lt. Van Buren from "Law & Order") in a female Starfleet admiral's uniform.
4: Kirk holding hands with Miramanee at the Obelisk/Temple in "The Paradise Syndrome", but with Alice Cooper photoshopped in over Miramanee.
5: Any female cast member of HBO's "Girls", photoshopped into a Starfleet uniform.