I heard the must toughen your nipples advice, too, when pregnant 11 years ago. Also heard lots of "you can't breastfeed twins."
The ones that make me most upset are the completely inaccurate comments from doctors.
DD had anesthesia at 16 months to open a blocked tear duct and I was told by the ophthamologist that she had to fast for 12 hours prior, including breastmilk. This for a child who hadn't gone more than 2 hours without nursing since birth. To his credit, when I presented him with lots of research contraindicating the need to fast from breastfeeding, he readily agreed. At least he was willing to learn.
When my twins were 2, eating some solids but still getting the majority of their calories from nursing, our doctor told me that my milk didn't "count" any more and that they needed at least 24 oz of cow's milk a day for calcium. WOW. 24 oz?!?! I never calculated the calories out, but I'm fairly certain that would be more than the total calories they consumed (besides my milk) in a day. That same day she insisted on testing their iron because they "must" be anemic. She didn't even have the courtesy to come back into the room and tell me herself that their levels were fine, she sent her assistant. That was the last straw w/ this doctor.
As my twins approached a year and beyond & were still nursing, I also got lots of "Oh, I could never keep doing THAT for SOO long" types of comments, like I was some sort of martyr sacrificing myself to breastfeed. No, actually, breastfeeding makes my life easier. They fall asleep quickly, they don't have tantrums, I never have to worry about not having a snack available. . .
My mom, who is a wonderful Grandma and has always supported my non-mainstream choices (she told me when I planned on having my 3rd at home that she didn't blame me because hospitals are horrible places . . . this from a woman who was a nurse), one time made some offhand comment that if I was still nursing when my twins were over a year, she wouldn't go out in public with me any more. I was so shocked to hear that from her and immediately called her on it. She now claims she never said that.
I'm so lucky to be surrounded by mom friends who also believe that breastfeeding until a child weans on their own, bedsharing for years, babywearing, etc. is just normal that it is now shocking to me when someone asks if my 3-year old (4 in Nov) is still nursing.