There’s nothing wrong with a little office fun. It keeps us afloat sometimes. But when something becomes mandatory, it immediately stops being fun. It’s just human nature. We hate being told what to do, like petulant children, especially at work. But where is the line between good ole work-sanctioned diversion and an event that nobody will love, most people will be annoyed at, and ultimately cost you some goodwill as a company? As an employer, you want to give some opportunities for fun to your workers. You want to help them break up the days and weeks, preventing them from cascading off into monotony. 

But you should probably do that during work hours. If you want to do something after work hours, it better be voluntary and you better be providing free stuff. Some companies don’t quite understand that, though, and force their employees to do stuff they don’t want to do. When, as an employee, do you say «enough is enough?» Maybe it would be being forced to spend your own money on a contest you don’t want to enter.