How do we get the boogers off

So my 4yo daughter will come over to my belly occasionally and rub it. So last night in all seriousness she says mom how are we gna get the boogers off of the baby. I was confused so i asked her to elaborate. She said a video on Youtube there was a baby and he had boogers hanging from his belly button.. Well ding ding it clicks. Umbilical cord hahah so im now laughing trying to explain to my 4yo what a placenta and an umbilical cord are while shes staring at me like im nuts