Spock more or less tormenting Rand after Kirk nearly raped her is pretty damned creepy.
THIS! When I first saw this (I was a kid), I thought nothing of the scene other than one that was supposed to be humorous. But subsequent watches as I grew older lent the dialogue, his delivery of it, her reception of his "joke" and just the entire exchange a strongly cringe-y feel.
Scenes like this (and episodes like Turnabout Intruder) force us to place TOS firmly in its time and excuse it for what it ultimately was: a 60s TV series.