The process of realizing I've actually already done something that I previously thought I had forgotten to do:

1. Freak out (i.e., "Crap! Why didn't I do ___? I really should have. I'm so dumb.").
2. Investigate later, and find that I've already done it (i.e., "Wtf, it's already done. I worried for no reason. Yay!"); be pleasantly surprised.
3. Be extremely unsettled by my utter lack of memory retainment (i.e., if you want something from me, you better count on reminding me a lot)