un-rememberable 

Adj., A word used to describe something that can't be remembered due to outstanding circumstances.

All the best 21st birthdays are un-rememberable

un-rememberable by TokingBeaver October 30, 2010

un-rememberable 

That one person you keep meeting but you never remember and so you introduce yourself to them as if you'd never met, even though they remind you they already know you.

You: Hey, I'm (name), nice to meet you!
Them: We met last week. Jesus I'm so un-rememberable....

un-rememberable by The Unforgettable February 21, 2014