Is this a joke...........?

I always get friend requests from ppl I don't know on facebook and I always get this weird call from this guy. I got a friend request from some girl who I don't even know and 0 mutual friends and Ive that at least like 2 times before. Could this be someone making a fake profile just to be nosey? I mean everything on my profile is private. And like 3 months ago I got a call from some guy asking for Dennis I said wrong number and he called the next day asking for Dennis and I said wrong number. 3 months later that guy called asking for Dennis and I said wrong number and he ok but he said it like he didn't believe me. Could this be someone that knows me and is making fake profiles, and prank calls???? Idk maybe it's me but what do you think???