Chubby refers to body type. In gay adult material it points to men with a fuller, softer build, and it sits alongside related body descriptions such as bear or chaser, which carry their own meanings around grooming, hair or attraction rather than size alone. The word says something about how a person looks, not about what happens on screen. Terms found nearby here, like anal, solo, jerking, cumshot or toys, describe acts or formats and work on a separate level.