Q: When do doctors get mad?
A: When they lose their patients! (patience)

Explanation: Patients are the people who go to see a doctor.  When you go to the doctor, you are a patient (noun).

Patience (notice the spelling difference) is the ability to wait without getting upset, the ability to explain something without getting upset, the ability to endure a difficult situation calmly.  Getting mad quickly is the opposite of patience.  Road rage is the opposite of patience.  You probably know people who are the opposite of patient (adjective).

This joke is funny because both words sound the same.  A doctor who has patients who decide to not see him or her, might lose his or her patience, that is, get upset when fewer people make appointments.

I found this joke after listening to the previous joke’s song, Patience by Guns ‘n Roses.  Here is another way to think of patience: