Who's that Pokemon? No really...

Have you ever seen a Pokemon (especially one you should know, like from gen I or II) that you just totally forgot existed?

I did today. I ran into a Diglett on SS, looked down and was like 'oh shnaps, they made a penis pokemon?' Then I was like 'oh, wait, it's Diglett...' Granted I was distracted by something else before looking down and seeing the pokemon, but still...