Two children are in a doctor’s waiting room, and one of them is crying.
“Why are you crying?” asked the other child.
“I’m here for a blood test, and they’re going to cut my finger. “
When he heard this, the other child started to cry.
“Why are you crying?”
“I’m here for a urine test. “
This joke is included in the Black Book of Jokes. You can order it from here.