Oh, I see. Well, I'm pretty sure you can go in with no top already (at least as AMAB). Though, I don't know if that would block the flag that initially triggers the event.
Can't remember how mtf and too lazy but as far I could think, Have exhibitionist needed as per 4+ and more advance of its traits. Not odd enough, Only flat tits fine but skills needed and such for that to be able except streaker at night. But if i'll have my transman later, i can try cheat up and checked it out myself if, i don't forgot this thing.