Too many to list.
However, I shall list a few...

People who get "I" and "me" mixed up. It isn't that hard... if it is the object of a verb or a preposition, it is "me", if it is connected via a linking verb or is the subject, it is "I".
People who do not tip their delivery driver/waiter.
People who forget all rules of grammar, spelling, and punctuation when they are on the internet.
People who drive selfishly (e.g. don't use turn signals, don't obey the right of way, etc)
There are quite a few others for me, but those are the first ones I could think of (of which I could think XD)