One geometry pun is "What do you call a man who spent all summer at the beach?" The answer is "a tangent." This joke creates a pun on the word "tangent," which sounds like the phrase "tan gent."
Another joke is "Why couldn't the math professor's daughter buy her first car?" The reason is that "her parents wouldn't cosine on the loan."
The word "angle" is used in these geometry puns:
Q: What do you call an adorable angle?
A: Acute angle
Q:What do you call a crushed angle?
A: A rectangle
Q: What do you call a stubborn angle?
("Obtuse" is both a type of angle and a synonym for "stubborn.")
Geometry puns also play off the syllable "gon" that ends the names of many shapes.
Q: What do you say when you see an empty parrot cage?
A: A polygon
Q: What would you say if someone took your deck of cards?
Q: What do you call people who are in favor of tractors?
Two other jokes that use geometry terms are "What do you use to tie up a package?" and "What do you call a fierce beast?" The answers are "a chord" and "a line."
A succinct pun about this subject states that "without geometry, life is pointless."