time to ask a question that has probably been asked many times before...

how do i safely bind without a binder? i'm too scared to outwardly buy a binder because my transphobic family will find out and they most likely know what binders are and what they're used for. they will then probably call me a girl and say there's nothing wrong with my chest, but what can i use at home to flatten my chest? i don't have any sports bras that are smaller sized or anything, but i could probably borrow one from a friend or family member.