Acorn's Lament

What did the acorn say when it grew up?

Geometry.

(Geometry= "Gee, I'm a tree!")

Explanation

Experiment

Explain Bear

Listen here, genius. The joke is that "geometry" sounds like "gee, I'm a tree." An acorn grows into a tree. Get it? It's called a pun, which is like the lowest form of comedy, perfect for someone like you, who probably still uses training wheels on your bike.