Brit Milah, we have a big ceremony, and we cut the foreskin of the baby. The one who does this, is of course trained. He is called a Mohel. There is someone called a Sandak, who holds the baby when is getting the Milah. This is also the naming of the baby. The Rabbi says:" Vekara Sh'mo BeYisrael", and the father/grandfather says whatever he wants the name to be, and the name of the baby's father.