>>149746129
The best way, if you don't include the swim trunk with no top, is some formal wear, those still have a pretty masculine presence as long as it doesn't have clear for-female traits like skirts. Nothing is as much male-exclusive as dresses, skirts and such are female-exclusive, so reverse crossdressing is pretty different from standard crossdressing but a girl with the right figure in the proper formal wear can pass as a guy.