I have a couple ...
When LO was just a couple months old we were at my OH's sisters house. We hadn't brought anything with us, so I had LO sitting in his carseat on top of a plush blanket so he was comfortable. Than I had this bright idea to go sit in the kitchen with my OH and bring baby along. So I lift the carseat handle up ... but what did I not do? I didn't wait the the snap! So as I lift up off the floor, the seat goes forward and LO falls to the floor, face first. Thankfully I had not picked it much off the floor, but was so embarrassed my first mommy blooper happened in front of 5 other people who looked at me all crazy ... and I did not think my OH was going to shut up about it. I just sat on the couch after OH handed LO back and cried with him in my arms rocking him .... for everyone to see!!
Just today I had LO sitting up, and he hasn't mastered it yet. But he fell back on the floor and his head literally bounced ... he was fine except I made him mad for patting and rubbing his head and holding him close.
Then this one my OH did. We are working on sitting up and LO was in front of him and OH was sitting in a fold-out chair. Well LO fell back and hit the leg of the chair. Scared us to death, I was sure he was going to have a mark ... but nope, he was fine.