I love my friends, but I'll admit that I occasionally talk a little smack. But it's okay. Everyone loves to say that those who talk about you behind your back are not your friends, but I disagree. Think about it this way: sometimes you talk trash about your family, but you still love them. Friends are literally the family you choose, so it's also normal and okay to talk a little trash about them too.
The fact of the matter is that your friends, just like family, are going to get on your nerves sometimes. They are going to aggravate you and rub you the wrong way every once in a while. Anyone that you spend a lot of time around will eventually annoy you at some point and if they don't then somebody isn't being honest. And irritation (especially pent-up irritation) always leads to an argument.
Why start an argument when you can just vent about it? There's no need to pick an argument with your friend just because they took a little bit too long to respond to your text or because they canceled on you one time. That's just a petty argument and it's really about you being sensitive and not that your friend did anything wrong.
Sometimes the people you love do things that irritate you and get under your skin, that doesn't mean you need to pick a fight every time you get annoyed. People can be annoying and that's okay, go ahead and vent, let it out, get it off your chest - just say it to the friend that isn't getting on your nerves. It's better to do that than to let it build up and explode later on because your friend ~still~ has your earrings.
There's no need to ruin a good friendship just because you let the little things pile up inside you until you couldn't stand it. It's also not going to be fun when you ruin a friendship because you want to hash out every single one of your grievances no matter how small.
This isn't a free pass to say whatever you want about the people you surround yourself with. I'm just saying that you're allowed to vent and to talk a little smack if it helps avoid unnecessary drama. Now, if it's a constant issue, maybe go ahead and bring it up to your friend and hash it out because you also shouldn't bottle up legitimate issues.
Nobody's relationships are perfect, so there's no need to create excess drama every time one of your friends pisses you off a little bit.
Learn to let go of the little things, vent if you need to, and your relationships will be better for it.