"Oh, you're left-handed? That's cool."
If you're left handed you hear that any time you pick up a pencil or a fork. But is being left handed actually cool? Sure, you're cooler than right-handed people, but sometimes it really sucks. The world was not made for left-handed people, and it's the little things that really add up.
Sitting at Desks
There are, in fact, left-handed desks in existence. However, more often than not they are moved to less the ideal locations, or just removed from the classroom entirely. Or some right-handed person thinks they're better than the rest of right-handed people and takes them. Pro Tip: don't be an ass, and don't take my seat.
Scissors
This was very disappointing as a kid. Scissors just do not work. Left-handed scissors are a thing now but back then you were just known as the kid who couldn't cut things out.
Eating at a Table
If you're left handed you almost always need to sit on the left edge of the table, or you risk elbowing (and being elbowed by) your neighbors. The rest of the group might not think it's a big deal, but it's for the best.
Writing
Writing from left to right causes way too many issues. The biggest one being you have to drag your hand across whatever you just wrote. Your writing is smeared across the page and now the side of your hand. Sure it was cool to have a big silver smudge on your dominant hand in elementary school, but after that, you just look like you need to wash your hands.
Playing Sports
This is where it gets tricky. Maybe you write left-handed, but you bat right. Or vice versa. It's hard to keep track. One side is always better than the other, and for some people, it changes every time. If you lack coordination, you can always just say your left is your bad side. If neither side is good... you just have to settle for being bad at sports.
Cooking
You wouldn't think this would be a big deal, but most cooking utensils are not made for left-handed people. You can get away with certain utensils, but certain knives/can openers/scoopers will just never work for you.
Computers
I grew up in a house full of right-handed people, so there was never a left-handed mouse option for me growing up. But many people have to go out and buy a separate mouse just so they can use their computers like normal people.