What does citation needed means?

"Alright, sweetie, when someone slaps a 'citation needed' on something, it's basically a polite way of saying 'prove it or it didn't happen.' It's like when your friend claims they dated a celebrity but you need receipts before you believe them. In the world of facts and information, citations are the receipts that back up what you're saying. So, if you want to be taken seriously, make sure you've got the receipts handy, honey."