What are some fun rules to spice up a game of Uno?

Some fun rules to spice up a game of Uno include adding a "Draw Until You Can Play" rule, where players keep drawing cards until they can make a move, or implementing a "Reverse Rotation" rule, where the direction of play changes unexpectedly. Another option is to introduce a "Wild Card Challenge" rule, where players must perform a challenge before playing a Wild card. These rules can add excitement and variety to the game of Uno.