Stress
You pick up a hitch-hiker; a beautiful girl. Suddenly she faints inside your car and you take her to the hospital. Now that's stressful.
But at the hospital, they say she is pregnant and congratulate you that you're going to be a father. You say that you are not the father, but the girl says you are. This is getting very stressful!
You request a DNA test to prove that you are not the father. After the tests are completed, the doctor says the test shows you're infertile, and probably have been since birth. You're extremely stressed but relieved.
And on your way back, you think about your 5 kids at home.