'Championship Boxing' is a tournament shown on Squidward's television in the episode "Idiot Box." It is literally about boxes fighting.
Role in episode
It appears in a brief scene where Squidward was watching channels on the TV, containing box channels and this was one of the channels in the TV. However, this channel appeared only for a very short time until Squidward was annoyed since it was one of the network's showing boxes as the main highlight.