Wrong writing and saying of 'should have'
Many people mishear 'should've' and hear 'should of' instead. Same procedure with 'must've' and 'could've'

the thing that you don’t have when you’re phones percentage is over 20

A stupid way of saying "should have".

What idiots say instead of should have. It makes most people want to stab the offender to death.

Ignorant way of saying, texting, or posting on facebook the contraction of should have (should've). Especially pathetic when supposedly educated people use the phrase.

Misspelling of should've (should have)