Kirk forgets how the Vietnam War ended.
When a planet-size alien threatens to reproduce, the Enterprise becomes a giant contraceptive.
Kirk cheats at cards.
Kirk gets paid to do what he does best (and the other thing, too), and after he beats up his girl friend (twice), becomes ruler of another planet that fortunately hadn’t heard of the Prime Directive.
It’s a well-known fact that quadrotriticale occurs naturally only in 137-grain bread.
Kirk does his best to stop a killer cloud, but the crew has doubts about his sanity because they think he might be confusing it with just any killer cloud. Spock gives the OK to destroy it when he realizes it is an intelligent being.
Kirk loses his toupee.
The Enterprise visits another society so primitive that they’ve still gotten only last season’s episodes. Kirk then has to teach them how dishonorable and sneaky Klingons are.
Spock’s parents attend an intergalactic PTA meeting.
Kirk discovers that universal translators can not only translate languages they never heard before, but also determine an alien’s sex just by the sound of its voice, allowing him to avoid future embarassment.