Skreb can mean two things

i) A young pikey, townie, scally or chav. Usually aged between 10-14 years, they often ask questions such as 'Do you think you're hard?' and threaten to 'get me brother on you'.

ii) To spit, usually involving mucus.

When you eat dirt for the first time and leave your family to build a shack in the woods

A socially regressive term that occurs when one person in a friendship with another person sees the other person make a mistake, but is too afraid to call them out in any sort of lighthearted criticism for fear of a loss of friendship.

The term has an addictive characteristic in how the word sounds somewhat silly or cool, and therefore is used in repetition even by people who have a disdain for the word itself.

So, essentially, if you are a fan of this word, you're a skreb.