Answer:
David's father has three sons: Snap Crackle and ?
I have keys but no locks. I have space but no room. You can enter but can't go outside. What am I?
I am Invisible Man's drink at snack time
When you take away the whole from me there is always some left.
I run around the streets all day. Under the bed or by the door I sit at night never alone. my tongue hangs out waiting to be fed during the day.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?