That means if your child goes on a spending spree with the card, then you are just as responsible for that balance as your child. (valuepenguin.com)
Sadly, it is not unusual for one partner to go on a spending spree with jointly held credit cards prior to a divorce becoming final. (think-creditcards.com)
However, if your partner goes on a spending spree without your knowledge, you are both responsible for repaying the debt. (moneysmart.gov.au)