IOU
Meanings
An informal written document that acknowledges the existence of a debt
Examples
I cannot pay you now; do you accept an IOU? 
Non posso pagarti adesso; accetti un pagherò?At the Missouri lottery I won $ 10.000 in cash, not in IOUs
Alla lotteria di capodanno ho vinto 10.000 Euro in contanti, non in pagheròOrigin
IOU is the phonetic acronym of the words "I owe you"