The use of sharp with time
I've studied that you can use the word sharp with time, meaning punctuality. Are these sentences corrects?

1- I arrived at eigth o'clock sharp.
2- I'm meeting you at half past five sharp

It sound natural or it sound rude? Would you mind telling me other examples?

Question

The use of sharp with time
I've studied that you can use the word sharp with time, meaning  punctuality. Are these sentences corrects?

1- I arrived at eigth o'clock sharp.
2- I'm meeting you at half past five sharp

It sound natural or it sound rude? Would you mind telling me other examples?

Answer

The first one sounds just fine ("eight" is spelled wrong though), but the second one does not.  When you use "sharp," you always say actual time - one o'clock, four forty-five, etc.  
You could say something like, "half past five, on the dot," and it would sound okay.  But, "half past five, sharp," just doesn't have the right flow.
Most of the time, people won't perceive it as being rude, unless you are being rude in general before you say that.

Answer

Another good example would be:

Be there at 5:00 sharp!

By adding the word "shap" you are stressing the need to be punctual as if there will be some negative consequence if the person is late (like he'll miss the bus).

Answer

It's fine.  It means "exactly".

Check your spelling. It should be "eiGHt."

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