I don't get
angry, but I do cringe and get a touch of secondhand embarrassment for people that can't seem to grasp basic grammar rules (native English speakers) and I know it's not intentional disregard of proper grammar in favor of slang/common vernacular.
-Your vs. you're (just...
)
-Worse vs. worst (comparative vs. superlative = not interchangeable)
-It's vs its (contraction vs. possessive = not interchangeable)
-Then vs than (again, not interchangeable)
-Should/could/would of instead of have or the contraction
-Lacking subject/verb agreement
^ These are the most grating mistakes, IMO.