Calculus students will better appreciate this joke.
The guy gets on a bus and starts threatening everybody: “I’ll integrate you! I’ll differentiate you!!!” So everybody gets scared and runs away. Only one person stays. The guy comes up to him and says: “Aren’t you scared, I’ll integrate you, I’ll differentiate you!!!” And the other guy says; “No, it won’t do anything to me, I am e^x”.
Hope this joke will ya in Calc. tests.