Hilarity Ensues  
Jazmine: What's so funny?
Robert: Oh, nothing. Hilarity just ensued; that's all.
Jazmine: It did?!
— The Boondocks

Alleged consequence of any event in a Sitcom or cartoon which in the real world would result in hospitalization, a lawsuit, or dismissal from one's job, at the very least, up to and including possible imprisonment or death. Thankfully for our fictional friends, both the Rule of Cool and the Rule of Funny keep them safe (the latter more prominently).

Traditionally seen in the capsule descriptions of episodes found in programming guides: "Jimbo accidentally glues his boss to a golf cart and hilarity ensues." Outside of these descriptions, though, the phrase is usually used sarcastically, indicating that the consequences are anything but hilarious. The less charitable might say that hilarity is what happens for those hearing about it afterward.

Variants include "...with hilarious consequences" (more common in the UK), "wackiness ensues", and "hijinks ensue." In extreme cases "wacky hijinks ensue." Hijinks are often "aplenty." Compare Silliness Switch, when the hilarity is a choice in an otherwise serious medium.

Not to Be Confused with the webcomic Hijinks Ensue. Or with Humanity Ensues. When something serious happens and it's not played for laughs, you may end up with Reality Ensues. If the aforementioned hilarity is a lawsuit, it may be a case of Hilarity Sues.

Check this Stanford article (with link to the paper) on how to build a microscope (2000x) for a total of 50 cents (USD) in material costs. Youtube video.