set theory – Every element of the empty set is a donkey?

My teacher told me today that every element of the empty set is a donkey. I can not really understand this statement. When I asked him for clarification, he told me that every item in the empty set is also from me and refused to answer any other questions. I was a little offended because I'm pretty sure I'm not a donkey. Can professional mathematicians explain to me here
Did all this make sense or if the professor had ruthlessly been waiting for me?