Pin-up

In various Teenage Mutant Ninja Turtles comic books, pin-ups are assorted sketches and artworks printed as part of an issue, usually in the back pages and sometimes accompanying a section publishing letters submitted by readers. The pin-ups could show random or frivolous scenes, sometimes completely disconnected from the issue's story. They were historically common in Eastman and Laird's Teenage Mutant Ninja Turtles by Mirage Studios, and could also be encountered occasionally in Teenage Mutant Ninja Turtles Adventures by Archie Comics. Pin-ups have become far less common in modern comics, especially as it has become far more common for comic artists to publish sketches and promotional work on the internet, a resource which was not as publicly accessible in the 1980s and early 1990s when pin-ups in comic books were most common. Pin-ups are particularly scarce in  by IDW Publishing, which started its publication run in 2011.