I have had a few: The biggie is when you hand over a newborn baby to a female, they are so scared of dropping the baby that they grab the baby, hold it close to their chest, and take your hands/arms with them. When my kid was a baby, I accidentally felt up at least 10 different of my female friends this way. One time, a friend was staying overnight from out of town to see the baby--I got to hand her the baby when the friend was wearing a pajama top and no bra. I could make out her nipples with the back of my hand and everything.
In college, I had a gal sitting next to me. She dropped some paper and leaned over my way to grab it. She starting falling out of her chair, so I grabbed her, and ended up with a hand on her left breast and my arm on her right. They were really small, but really firm, like two little rocks poking my hand/arm. She took her time getting back up, and I didn't say anything, but she was completely red in the face. She adjusted her shirt, and never said a word. And never bent over again, either. Some girls wouldn't have cared, but she was truly upset about it, yet knew it was unintentional on my part and she couldn't do a darn thing about it.