put one over on me

If someone tells you that you put one over on them, it means you fooled, tricked or hoaxed them and they now realize it. If someone is fooled or tricked and they ultimately find out about it, they see that this person has deceived them in some way. By saying this person put one over on them, it is another way of saying they are admitting this person tricked them without them knowing about it while it was going on.