What are some of the things no one ever told you about a newborn/baby?

Up until a few days ago I thought my son (9 months) when he was a newborn had stomach problems or something because he would cry while pooping every. single. time. And it wasn’t hard or anything he would just cry until it was over. Well my cousin just had her baby a month ago and she asked if my son ever cried while he pooped.. I felt so relieved that my baby didn’t have any problems.