My toddler loves poking belly button

My toddler has a bad habit, he likes to poke his belly button whenever he's taking his milk. After google online I find out that it's quite normal this happening and not just him other toddler doing the same. As long he's not harming himself, he also likes poking his dad's belly button.

He would be drinking his milk and poking belly button at the same time while watching TV or just looking at you. There was a time he was wearing the monkey outfit, he couldn't touch his belly button while having his milk. He screams for it and he's feeling discomfort for not able to touch or poke his belly button while having his milk.

Anyway it's best to watch out for toddler, you never know what they would grab to poke their belly button. I caught my toddler trying to poke his belly button with sharp object. Right away I remove the object from his hand! I wouldn't want him to hurt himself.