1986, Dir. Leonard Nimoy
This is another one that's stuck with me, despite the fact that the reference to Mormonism is ambiguous at best, and more than likely unintentional. Although for me, in the theatre as a little boy, there was no doubt that I was sharing a secret, highly esoteric joke, and that mixed-up Kirk was inadvertently linking Spock to the Mormon Church at Berkley in the 1960s. The Internet has reassured me that I am not alone in my Mormon-centric view of this exchange between Captain* Kirk and a blonde whale doctor from 1986 San Francisco. Thanks Internet!
*I know he was an admiral when the scene took place; he wasn't demoted back to Captain until the end of the movie... So what if I was a Star Trek nerd? Thanks to J.J. Abrams, that's cool now...
Context: In the future, the earth is threatened because apparently the song of humpback whales placated some destructive alien force, but the whales are long since extinct. So the crew of the USS Enterprise dutifully travels back in time to the year 1986. They have some difficulty in adjusting to life in mid-eighties San Francisco, and Spock in particular sticks out like a sore, alien thumb. For instance, while on a tour at an aquarium, Spock dives into a whale enclosure and performs a Vulcan mind-meld with the giant mammal. Understandably upset, Dr. Gillian Taylor (Christine Hicks) who works at the aquarium, kicks Kirk and Spock out. Later, she passes them on the road in her truck. Kirk attempts (unsuccessfully) to explain why his companion acts so weird and Vulcan-y.
Exegesis: As I mentioned earlier, it's entirely possible that this scene doesn't belong on this site. Essentially, Kirk transposes two letters when he makes reference to the psychotropic drug LSD, rendering it LDS. As a young boy when the film came out, I was convinced that the writer had intended Kirk's malapropism to change the meaning of the acronym from its intended "lysergic acid diethylamide" to "Latter-Day Saint", a shorthand I was familiar with, but which it occurred to me much later, few others would be. It's perhaps more likely that the joke was merely Kirk's fuzzy 23rd century mind comically misremembering the order of three letters. He could have said "DSL" and achieved the same effect. Nevertheless, I am including the clip on this site, on the slim chance that when Nicholas Meyer (et al.) wrote the screenplay, they had "Latter-Day Saints" in mind when they put those words in Kirk's mouth, even if the resulting acronym makes no sense in the context of the sentence.