Q: How did Ben Franklin feel about discovering electricity? 
A: He was shocked!

Explanation: First of all, Ben Franklin did not discover electricity (learn more about the electricity here).  What he did was an experiment to prove that lightning was electrical.  It is a good thing he wasn’t killed!  Anyway, “to be shocked” is to be surprised.  “Shocked” is also what you feel when a bit of electricity enters your body.  This joke is funny because of the double meaning of the word shocked.