This here might be sometimes a bit inconsistent, but basically everything, where a character gets treated more like a pet or animal, rather than a person. This also includes dressing up in such a costume.
Jen the Gynoid by EssexEye
In this wonderful skinsuit story by EssexEye, Mark and Robin get a very special kind of costume. Robin bought a skinsuit of a huge seven-foot-tall woman and wishes for Mark to wear it and “have his fun with Robin”. To actually fit into the suit properly, it also came with a unique kind of exoskeleton one would wear underneath the suit to actually have the body and proper proportions. Mark is sceptical about the entire thing, but he had promised Robin to at least try it. Being quite surprised about the features of the exoskeleton, Mark is overwhelmed when he first finishes getting into the mechanical suit underneath and even more stunned, once he has completely hidden away his robotic features underneath the skinsuit. Looking into the mirror, he finds a perfect living version of the giant, tanned and blonde-haired woman and can barely believe that it was actually him standing there. Over the winter holidays, Robin and him get into all kinds of adventures with their new toy and at one point even get a few more possible suits to wear… Jen the Gynoid by EssexEye Part I Original on DeviantArt When Mark and his girlfriend Robin are having some trouble keeping things interesting in the bedroom, Robin has a solution. The solution in question is seven feet tall, and she’s gonna push Mark way outside his comfort zone. ...