Snot fair

exp.

An expression used to describe how dissatisfied someone is with events dat have just transpired.

In use

Daddy: "Go to bed now ye little mickey man!" Mickey: "Snot fair!"

Let Lawrence Muck translate it to posh English for you
Lawrence Muck

What ho! Would you like me to translate 'Snot fair' in use for you?

'Off to bed with you now, you little rascal!' 'That is not fair!'