It's a game numerous childhood memories are drawn from, sprawled out on the floor dishing out draw 4s to your friends.
But a new revelation has changed everything we thought we knew about this mighty game.
According to an enthusiast, we've been playing UNO wrong this whole time.
LaToya McCaskill Stallings was doing some heavy reading of the rules and discovered we've been using the draw 4 card incorrectly.
"So it's taken me 35 years on this earth to realise that I've been playing Uno wrong since I was a kid," wrote LaToya in a Facebook post, alongside a snap of the official rules.