A celebration where guests bring diapers instead of standard baby-shower gifts is called a diaper party.
A diaper party is a gift-focused variation of a baby celebration in which attendees are asked to supply disposable diapers, often in place of ordinary presents. The practical goal is simple: newborns and infants use diapers continuously, so a stockpile can be particularly useful for new parents.
Diaper parties are sometimes organized for fathers or other male friends, but the concept is not limited to men. They may be held separately from a conventional shower or combined with a larger gathering for both parents.
The term is distinct from a diaper raffle. At a diaper raffle, guests bring diapers for entry into a prize drawing; at a diaper party, bringing diapers is the central gift-giving custom. Regional vocabulary also varies, with “nappy party” more likely in places using “nappy” for diaper.