Those who brag...

People who constantly brag about a certain aspect of their life tend to get on my nerves. However, it is sometimes tolerable, if the person actually is excellent at that particular skill.
BUT... If you do not excel at a particular aspect of your life, please do not brag about this skill in front of me.
Another thing is people who think they are excellent at a certain aspect of their life, but the only opinion they have is their own. If you're opinion is the only one you're going by, maybe you should ask a few people before you start to brag. Because, just be asking a few people, you could find out that instead of the superb athlete you think you are, you're merely an average athlete competing against sub-par athletes.
A lot of people who brag about a certain aspect of their life don't like to take criticism about that aspect. They think that there are so good at this aspect, that nobody could tell them what to do. However, since these people do not excel at this skill, they should realize that people are merely trying to help.

Examples for those who need it:

# 1. If you know you are an excellent football player, but you are only average in basketball, do not brag about how good you are in basketball. If you want to brag about how good you are in football, thats cool, you'll still be annoying, but at least you'll be able to back it up. However, once I see you on a basketball court, and see that you are merely an average basketball player, everything you critique after that is in question.

#2. You think you are an excellent basketball player, because you are always beating your little brother and his friends in basketball. You are dominating when you play against them. You decide to go play against your friends your own age, and realize that you are only capable of the same things as them. You have just found out that you are not the excellent basketball player you think you are. You now know you are just an average basketball player for your own age.

That's what grindz my gears.