Can you challenge a Wild Draw Two or Wild Draw Color card if you think it was played illegally?

Yes, you can challenge a player if you suspect they played a Wild Draw Two or Wild Draw Color card illegally (i.e., they had a matching color card). The challenged player must show their hand, and if guilty, they draw the penalty cards instead of you. However, if the challenged player is innocent, you must draw the original penalty cards plus an additional 2 cards.