I hide my boob quite well on a day to day basis. the only time you can actually tell they exist is when I'm out on the town and chose a nice top.. (don't strap them down)
I had been training with a guy for a while and normally im a oversized t-shirt with some pl'ing shit on it.. the other day i had a muscle type wife beater shirt (yea yea.. lol) with a hoodie over it.. got hot and took of the hoodie and he was like... shit.. I didn't know you had knockers! lmao!