The name for a person that gets so drunk that they fall asleep on the floor and wake up to find they have vomitted and shit their pants.
"Omg! That girl was so drunk last night she deffinetly pulled a sleepies and poopies...and that guy guystill had sex with her..but not in the butt, obviously!"
It's when you have a late night conversation (usually while on the phone), while very sleepy. The next morning, you forget what you were talking about towards the end of the conversation.
Guy 1: Remember what we talked about last night?
Guy 2: Uhh... No, I think I have sleepnesia...
Often a general lack of energy, even after an adequate night timesleep caused mainly by boring college classes or nothing to do. It is very common to young adults and teenagers.