"Outlander" isn't known to shy away from sexual imagery — but there's one infamous scene that made star Sam Heughan squeamish.

The 42-year-old actor has played the heroic character from the Scottish Highlands for six seasons of the Starz series, starting in 2014.

Heughan recently released his memoir "Waypoints: My Scottish Journey," and he's getting candid on how the graphic sex scenes have affected him.

He spoke of one particular scene in Season 1, when his character, Jamie Fraser, is sexually assaulted by his enemy Black Jack Randall (Tobias Menzies). Heughan has said he was frustrated when producers added an "unnecessary" shot of his penis in the scene.

"This wasn't a moment where I felt that being naked would add to the horror of what Jamie undergoes in that castle dungeon as a form of punishment, subjugation and humiliation," Heughan wrote.

"I pushed back, reasoning that nudity sexualized a horrific experience for my character, and it sparked quite a debate," he explained.