Trying to recall where and when you spent all your money normally when that said money is needed. Occurs because of bad spending habits and fucking awesome party nights.
"Dude, I'm so bad with money! It just disappears."
"You might have spending amnesia. I remember you lost at beer pong then hit the pubs with those trannys.'"
The money you have left after you have paid all your bills for the month. This is money you can spend on whatever the hell you want or save towards something big.