Ladies: How did you discover your nipples as an erogenous zone?

How did you realize your nipples are an erogenous zone? Playing with your boyfriend? Playing with yourself? Doctors exam?

Maybe I'm weird, but mine are not especially erogenous. Touch there is only slightly more stimulating than touch on any other sensitive part of my body, like my face or fingertips.

I do like what it does to my partner to play with them, even if it doesn't do a lot for me.