Codename: Kids Next Door Mission Weekend was a 51-hour marathon that ran on August 8, 2003, to August 10, 2003. Although the main focus was on Kids Next Door, although other cartoons were featured.
The main theme was that the KND wanted to build a satellite to broadcast their own private network. During commercial breaks, Cartoon Network aired special bumpers, featuring spliced together footage of Kids Next Door characters interacting with characters from the other shows. Numbuh 1 stayed at the Treehouse, while Numbuhs 2, 3, 4 and 5 did the interacting.
There is also a game tied to the marathon titled Operation: S.T.A.T., where viewers could use the clues they collected to find parts to help build a secret spy antenna.
There is no known footage of the event and is considered lost. However Operation: S.T.A.T. is still around There are also articles on the Cartoon Network and Lost Media wikis, and 2 surviving ToonZone threads from August 8th and 9th.