10) Throw it off a cliff to see if it bounces.
9) Dress it us as John Rocker in New York.
8) Mail it to a taxidermist.
7) Tell a feminist it is male.
6) Tell it that its mother is a donkey (I don't know why this would
kill it but it seems like it would work).
5) Sell your soul to the devil in exchange for a visit to the mule.
4) Send 5 dollars to the Retarded Sheep and I will send you a dead
mule to exchange with the live one.
3) Send its owner a dead fish in the mail and tell him that his
mother will sleep with the fishes unless the mule is dead tomorrow.
2) Make it watch "Three's Company" 24 hours a day (this
method may be the quickest, 2 episodes max).
and finally, the best way:
1) Mule Tipping.