Because players see their avatars from a third-person perspective from behind, men are confronted with whether they want to stare at a guy's butt or a girl's butt for 20 hours a week. Or as the study authors put it in more academic prose, gender-switching men "prefer the esthetics of watching a female avatar form." This means that gender-switching men somehow end up adopting a few female speech patterns even though they had no intention of pretending to be a woman.
When men play female avatars in online games, they change the way they speak to conform to female stereotypes—but the way they move betrays their masquerade.