Face paint is body paint worn decoratively on the face. It has appeared multiple times in the Teenage Mutant Ninja Turtles franchise.
IDW
Face paint has had its most significant appearances in the IDW continuity.
Inspiration
Sophie Campbell has officially contributed to TMNT comics since Tales of the TMNT volume 2 in the Mirage continuity, where she illustrated some of the series frontispieces, as well as the cover art for Raphael: Bad Moon Rising.
Unofficially, Campbell also created the webcomic Teenage Mutant Ninja Turtles: Secrets of the Ooze, which is a reimagining of the events of the 1991 film Teenage Mutant Ninja Turtles II: The Secret of the Ooze. But in her character designs for this webcomic, the Turtles and Alopex were shown wearing not bandannas, but vibrant color-coded face paint patterns.
The Turtles
Later, similar face paint designs appeared as an easter egg in TMNT #89, though Campbell was not directly involved in the production of this issue. In this story, Splinter was shown his death in a possible future at the hands of his own sons, the Turtles. These future Turtles were shown wearing Secrets of the Ooze-style face paint, though only future Leonardo's face paint closely resembled the pattern worn by his counterpart in Campbell's webcomic.
Future Lita wearing pink face paint.
After Campbell was appointed lead writer of the IDW continuity starting with TMNT #101, her Secrets of the Ooze-style face paint designs reappeared in TMNT #105 as worn by a time-traveling future version of Lita, now a ninja of the Splinter Clan wearing pink face paint.
Rocksteady
In the miniseries Bebop & Rocksteady Destroy Everything!, Bebop and Rocksteady lived over a year of their lives back in the prehistoric Cretaceous period as henchmen of rogue time traveler Savanti Romero. (The Cretaceous scenes of this miniseries were illustrated by Sophie Campbell.) Rocksteady's appearance during this time included red face paint around his eyes. Even after returning to the present day and leaving Savanti's service, Rocksteady kept his face paint until the events of Bebop & Rocksteady Hit the Road #2, when the duo decided to try to make a new life for themselves in Houston, Texas, and Rocksteady removed the face paint when started looking for a real job.