Question

"tear me off and scratch my head, what once red is now black. what am i?

Answer 1

Match

Explanation: you scrape the red part of a match on the box, as the match burns, the “head” turns black.

Answer 2

a match!

Step-by-step explanation:

y'know how you take a match from a match box and you strike it against the rough part to light it? that's the "scratch my head" part and then once it lights, it burns, so it turns black.