First it would be nice to ask him what his name is, and then you can ask him to tell you where you two met. If you still cannot remember him, you can ask him to tell you the names of some of his friends that hang out with him while you were dating or if he knows some of your friends. You may also ask him where he used to live while you were dating and for how long you dated. It is important not to meet the guy if you cannot remember him because he might be a dangerous person and it would be polite to inform him that you do not know him and he should not contact you again.
Ask that boy whats he smoking if he say nothing den ask him what does he knows about you and if he know a lot ask him does he know anybody u know and if he say yea make sure your asking questions about those people and if he knows 2 much about one person den u have to figure someone is trying to pull a prank or hang the phone up>!!~