Probably not a proper couch gag since it only happened once, but in the first issue the title/credit box comes a page or two after Spider Jerusalem hears his editor's voice on the phone and, surprised, says, "The whorehopper!" The editor is credited, in that issue, as the "whorehopper".
A more proper example: at the end of each issue, the three eyed smiley face would be shown in a way somehow related to the content of the issue (walking in the rain, smoking a cigarette, etc.)
In Stan Lee and Steve Ditko's run on The Amazing Spider-Man, each splash page would contain some kind of gag in the credits, usually replacing "written by", "drawn by" and "lettered by" areas.
Each of the longer Sam & Max: Freelance Police comics carries a title gag in the form of "Based on the [Media Type], [Silly Title]", such as Based on the famed Beat-generation novel, "Sam and Max Drive Around in a Car" by Bucky Kerouac. This tradition is carried over to Season 2 and 3 of Telltale's series of adventure games. The episode "Chariot of the Dogs", for example, is "Based on the best-selling addled-brained musings of noted aliens-made-all-our-stuff theorist Erich von Dannyohday"
Bongo Comics' The Simpsons usually credits Matt Groening with a different title in every issue.
The Wicked And The Divine: Every chapter begins and ends with the icon wheel, showing representations of each god as well as their status.
Some sections of the wheel are empty, representing gods not yet known by the media.
Dead gods have their icons replaced by skulls.
Once Luci is arrested, her icon has bars over it.
When Baphomet bursts onto the scene, his icon appears for the first time in the wheel while wreathed in fire.