Verified answer

debit to Cash Over and Short for $2

Each time you buy something, you're supposed to get a receipt from the store. So theoretically, if you've spent $80, you would have collected receipts for $80. If your petty cash fund started with $100 and you spent $80, you should still have $20 in your petty cash drawer or petty cash box, but you have only $18, which means you're short by $2, i.e. you've lost $2. Perhaps some cashier in one of the stores shortchanged you, or you dropped some coins totalling $2, or whatever, but you've lost $2. Accounting-wise, you have to recognise this loss by debiting Cash over and short $2.