A Big Chris is a man who suffers with micro penile disorder, this is where the males genitals are unnaturally miniature. Also could be referred to someone who deals prime hydration.
*Calls Big Chris* "hello, you need some prime hydration? I will send it to Africa and back and then send it to you even though we are both in the uk" says Big chris whilst using a magnifine glass on his repopulation device.