Two years after my heart attack, I was teaching my college course when I felt discomfort in my chest. I paused the class to pop my medication and felt better quickly. 

“Now, if I ever do have a heart attack,” I told my students, “I will give extra credit to whoever gives me CPR.”

One of them shouted out, “How much?”

One Liner

The best way to discourage Knock Knock jokes is just by saying, “Come in!”