Star Trek: TOS

"It's an emotion detector." McCoy studied them both closely.

Kirk reached out to touch the smooth archway, half expecting McCoy to protest. He did not.

"See, the natives here had developed robots that looked close enough to a living person that couldn't tell the difference. Except for one thing."

"Emotion?" Spock raised an eyebrow.

"Exactly. That's mostly a glandular thing. Only someone capable of emotion can pass through those gates."

Kirk's lips twitched as he walked through. McCoy followed.

Spock remained, staring.

McCoy laughed, waving a hand. "I'm joking. It's just a doorway."

Spock remained. Eventually, turning, he walked away.

"Listen Bones, just between you and me..." Jim set his glass down and turned to his friend. It was late, the bottle was nearly empty, and the evening was pleasant.

"Yes, Jim?" Bones smiled up at him with the same inscrutable sardonic smile as always.

"Back on the five year mission... why all the fuss about my diet? All the food was perfectly balanced in nutrition anyway. And those workouts you made me do. A shot could have done the same thing."

"Oh, Jim..." He smiled, taking a deep sip. "What's to say I didn't like to see you sweat?"