I do this all the time! Usually it's with people from my church or people that my parents know; I know 100% that I know them, I just have no idea who they are or where I've seen them. Then I just be my usual self (adults always love me for whatever reason) and no awkwardness arises.
I've only done this a couple times with my peers. Once was at TIP (nerd camp; major props to anyone who's been there). I met a girl and hung out with her and some others for about an hour (very cute, she would be very memorable normally) and then saw her the next day. I said "You look really familiar, were you here last year?" "I'm Jenna, Patrick. You met me yesterday." Luckily she seemed amused by it. Another time was last year; I met a girl for the fifth time before I remembered her; I still feel really bad about it.
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I'm never gonna dance again, Aspie feet have got no rhythm.