9 of the most annoying grammar lapses

“the usage of correct grammar and good style is the hallmark of an educated (in grammar and writing) mind and disciplined (in grammar and writing) thought. as such it should recognized and encouraged. its absence should serve as a warning to readers and listeners of a concomitant lack of rigor in development of any underlying premise.” -- anonymous

let us start with two of, by far, the most irritating errors:

1. the use of your and you're

"your" is a possessive pronoun. "you're" is a contraction of "you are". it is very simple to understand; it doesn't take a genius to remember it and put it into practice.
so don't say, your my friend.
or, you're smile....
example: your writing is compromised if you're always using your instead of you're and vice versa.

2."did" is always followed by the present tense of the verb.
incorrect: after all, he did talked to the judge.
correct: after all, he did talk to the judge.

3. the subjunctive mood is the only occasion that it's correct to pair up a singular noun (or pronoun) with the verb "were".
otherwise, observe the golden rule singular noun, singular verb. plural noun (except collective), plural verb.

a verb is in the subjunctive mood when it expresses a condition which is doubtful or not factual. it is most often found in a clause beginning with the word if. it is also found in clauses following a verb that expresses a doubt, a wish, regret, request, demand, or proposal.

examples of subjunctive mood: if i were younger, i would have accepted the dare.
if my father were a lot more tolerant, my sister would not have run away.

4. still on verbs category, perfect tense subcategory: you always use the past participle form of the verb with auxiliary verbs like "has" and "have" such as: has gone, have told, have showered, has conducted

5. unless you're rapping, do not use double negatives, like "i did not see nobody."
correct: i saw nobody or i did not see anybody.

6. saying "stuffs" is wrong! it's just stuff. i wish for hellfire to come whenever people say stuffs, and furnitures, and equipments.

7. loose vs. lose . the former is an ajdective, the latter is a verb. it drives me crazy when people interchange them! the two words do not sound alike and their meanings are not the same! same is true with pleased vs please.
7a. affect vs. effect. affect is the one that does something. effect is the result of doing something.
7b. advice vs. advise. the first word is a noun, the second word is a verb.
examples: we will lose the shipment if those knots are loose.
what a loose woman! no wonder she has lost (past participle of lose) all her friends.
my wife is very pleased with your painting, can you make another portrait please?
i am very pleased with the group's perfomance, can i schedule them for another show on friday, please?
smoking has bad effects in your respiratory tract.
smoking gravely affects your health.
please advise me if i should follow my boyfriend's advice.

8. review the use of apostrophes. (incidentally, this is related to annoying error #1) here's a good quote (and a good time to practice your level of comprehension too)
"it's it is when it's it's and it's its when it's not."
- unknown

9. ignorance is not an excuse. do not say what's important is the meaning, not the sentence construction. grammar helps convey meaning. if you can't do it right, then don't write at all. (at least not in the english medium)