Some of my math jokes which motivated by Pramod Achar:

• If a mathematician want to be an assassin, then what would the weapon of choice be? The Killing form.

• What did Grothendieck get for himself on his high school graduation day? The Grothendieck ring.

• Quantum Group and Lie Algebra went to get a hair cut. Afterward, Quantum Group said to Lie Algebra: "you chose a very nice hair style". Then Lie Algebra replied: "U_q".

• Why is Victor Kac sad? Well, because of Kac--Moody algebra.