Is anybody else just now finding out about this rule in Uno? I feel like a lot of games would have ended differently using the Wild Draw Four Card properly.

That one card that holds the power to completely make or break a hand of Uno has special rule that most don't know about. You ever feel like somebody just threw down a Wild Draw Four just to spite you? Turns out you can call BS on them.

A player is only allowed to play a Wild Draw Four if they do not have a card that matches the color of the last card laid down. If you successfully challenge them, they have to draw the four cards instead! There's more, the text below comes directly from Uno's rules:

This card allows you to call the next color played and requires the next player to pick 4 cards from the DRAW pile and forfeit his/her turn. However, there is a hitch! You can only play this card when you don’t have a card in your hand that matches the color of the card previously played.

...

Note: A Player may play a “Wild Draw Four” card even if they have a matching number or word card of a different color in their hand. If you suspect that a player has played a Wild Draw 4 card illegally, you may challenge them. A challenged player must show his/her hand to the player who challenged. If the challenged player is guilty, he/she must draw the 4 cards. If the challenged player is not guilty, the challenger must draw the 4 cards, plus 2 additional cards.