Whether you prefer basketball, soccer, football, tennis or any other sport, all of these games can easily be turned into themes. Football will be an easy, much-appreciated choice for an adult Super Bowl party, and volleyball will obviously be the expected theme at a high school volleyball team banquet. However, practically any sport can be used as the decorating scheme for a child's birthday party. Napkins, plates and cups are often sold to match a sports theme event, and since most cakes are round, they can be decorated as soccer, basket or tennis balls. The party activity is simple -- just buy the sports equipment needed to go along with your theme, and referee a friendly game in the backyard.