In no-gi grappling, practitioners wear – you guessed it – no gi. Instead, they usually wear attire associated with surfing, specifically rash guards and board shorts. Ultimate Fighting Championship aficionados might be used to seeing male mixed martial artists in either only compression shorts or compression shorts under board shorts, but no shirt. And female mixed martial artists tend to wear sports bras, perhaps a rash guard, and compression shorts and perhaps board shorts. So there are a variety of options, though straight grappling academies tend to prefer students to cover up on top; unlike the professional mixed martial artist, typical grappling students have no financial incentive to put their faces that close to somebody’s bare armpit.