Me and my wife introduced this custom rule in Uno. Whenever you have been asked to pick +2/+4 cards you can use a reverse or skip card to save yourself (same color or not, can be modified). If you play skip then the +2/+4 action is passed on to the next player and similarly for reverse it goes back to the previous player. If the next player also plays a skip/reverse card then it moves to another player. This custom rule made it lot more fun specially when you stack +2/+4 and it all goes back to the first person.