Always write it down. You will not remember it later. That's the horrorterrors lying to you.
I wrote it down but I lost it, what now?
Where did you write it?
On the paper...
Well, I'd say try retracing your steps to see if you can find it, but if you threw it out it might be too late. I typically just find writing something down does make it easier to remember it even if I don't read it later to remind myself.
Oh, I remember what I wrote down. I'm just upset that I lost the paper. :( I didn't know what to do.
I'm sure that Slender fellow will find it.