Pootan is a bizarre but popular TV show within the series. Some believe that Pootan is a deprecate parody of the Cromartie series itself, but the author has only said that the idea behind Pootan was showing how something bad can be popular, too.
The show only has two characters - Pootan with a white costume and Poo with glasses and a pink bunny-like costume. They are very vaguely defined - not even the author knows why Pootan likes doing pottery or crushing sesame seeds, or even what animals they are supposed to represent.
The show is very popular in-universe, and all of the characters like it with the exception of Noboru Yamaguchi.
Usually the show is in the background, but some stories feature it as a central theme, including one where Freddie becomes a replacement for Pootan's actor.