Melonie is right about all the laws of physics, of course (Heisenberg's Uncertainty Principle? I'm not sure about that! LOL!).
Here's a little anecdote for you:
A couple of years ago, I was on vacation on Kauai in Hawaii. We decided to take a helicopter tour of the island (it was spectacular!) and I had no idea this was going to present a genuine problem for me! Imagine, if you will, a six passenger helicopter (the seventh person was, of course, the pilot). Two passengers (a woman and a small **09**) rode up front with the pilot. Four of us were squeezed into the back, and I mean SQUEEZED! There were two men, a boy, and me. I was on the left, right behind the pilot. These things aren't designed for roomy comfort to begin with, but my boobs were like an extra passenger! I couldn't even raise my arms!
On another note, that woman you overheard talking about her bra straps hurting was wearing the wrong size bra! If the straps hurt, the bra doesn't fit right...the straps aren't supposed to support the weight, just help positioning. Of course, I'm sure you're just going to tell her, aren't you? LOL!
My shopping life is further complicated by letters! Between trying to find HH cup bras and AAAA width shoes, I have quite a time! LOL!