A parable passed down for generations describing the futility of the unintelligent to perform simple tasks.
Since ancient times, when an imbecile, ill-advised coworker or friend has attempted an assignment beyond their capabilities, they are often compared to a monkey endlessly trying to fix an engine that won't start by beating on it with a hammer, because monkeys do not possess the skills of a mechanic.
After being shown how twice, Dannever did learn how to open the fence, so it rained on him a few hours later. He was just like a Monkey Beating An Engine With A Hammer that day.
While our lifespan is the number of years we will live, our healthspan is the number of healthy years we will have and our sexspan is is the number of years we will continue to be healthy enough to continue having an active sex life.
A lighthearted reaction upon receiving disappointing news of some sort. Usually something that isn't a particularly a big deal, esp. when it primarily affects someone else - sort of a mild schadenfreude. Sometimes doubled or tripled, and possibly said in a sing-songy voice for added comedic effect to imitate a muted trumpet, which is how the meme originated.
You didn't get any napkins with your takeout pork fried rice? Womp womp.