You have poor grammar, i.e., you don't know what you're doing...

There is nothing worse (note the exaggeration) than blatant misuse of the English language. 


When someone writes "your" but really means "you're" makes me cringe. I equate it to an adult who can't properly use a knife and fork. 


Imagine my surprise when a friend who often writes "then" when she really means "than" pointed out my improper use of the Latin abbreviations i.e. and e.g.. 


I.e. or id est means that is (to say) while e.g. or exempli gratia means for example. 


Thankfully theoatmeal.com has taught me never to misuse these abbreviations ever again: 

Lesson learned.