People Use Way More Than 10% of Their Brain
This has been proven back time and time again to the point that the age-old argument no longer even makes any sense. The human brain is roughly 3% of the body's mass, but it uses 20% of the energy that your body has stored. So technically, your brain uses 120% of its capacity.
Left-Brain and Right-Brain People Do Not Exist
Even though it is true that the human brain allocates different locations for different things, the human body uses both sides equally. The brain isn't as simple as "one side does this and the other does that." Our brains do thousands of things at once that spans over millions of neurons in a millisecond. Nobody uses one side of their brain more, but people tend to enjoy doing certain things over other things.