Good Riddles

Question: after Lindsay got grounded, why did nobody see her in her room?

Question: What small place has a lot of money?

Question: A man and his son are in a terrible accident and are rushed to the hospital in critical care. The doctor looks at the boy and exclaims "I can't operate on this boy, he's my son!" How could this be?

Question: I have no wings but I fly,
I have no teeth but I bite.

What am I?

Question:

The dirtier I am, the whiter I get,
Leave a mark on me when you stand, I'll leave a mark on you when you sit.

What am I?