When you forget someone's name while you are introducing them to someone else so you can figure out what the other person's name is, since you've forgotten that too.
Natalie: Hey Tom!
Natalie: Remember me?
Tom: Of course I do. Oh, I want you to meet someone, Uh. This is.. Shit guys, I'm sorry, I just totally had Namenesia. I'm really, really bad with names.