someone who constantly corrects another's grammar...
to the point that you want to kill them.
but they can't help it, it's almost natural.
but sometimes, the errors are obvious.
see dumbass OCD
"you can't say that! ain't isn't a word, it's don't! and you had a double negative! you have to say 'i don't have any more money'
"oh right! i forgot you are OGD! i better work on my grammar!"