Again, while I am not offended by what the shirt said, I wouldn't wear it either.
Personally I don't want to walk around with a shirt on that says "ta-tas" on it

I see where you are coming from with the point of "is it really necessary to use the slang" and it's not, but t-shirts with edgy sayings are all the rage right now and this shirt fits into that category while touting an awareness for a worthy cause.