I used to work at Disney World. Here are 10 things I never buy at the parks.

If you're on vacation and want to spend $3.50 on a bottle of water, be my guest. But I never buy water at the parks.

It's a waste of money, especially because you're allowed to bring your own bottles in.

The old trick of the trade is to ask for a water cup at any quick-service location, but frankly, I don't like the taste of that water. Instead, I purchase a few cases of water on my way from the airport and carry them in a backpack around the parks.

It saves me money and keeps me hydrated in the Florida heat.

I'm usually one to justify spending an exorbitant amount of money on anything shaped like Mickey Mouse. But M&M's is where I draw the line.

I was walking through the Main Street Confectionery in Magic Kingdom one day and came across M&M's in a Minnie Mouse container for $39.99.

The price is outrageous, and they're destined to melt in the Florida heat before you can even eat them.

You're better off getting some candy at a gas station on your way home.

When I want autographs from Disney characters, I bring a pen from home.

Unless it's a super fancy ballpoint pen, I can't justify spending $8 or more on one at the parks.

Pro tip: If you ask a character attendant (the employees stationed with the characters), they'll usually have a pouch filled with permanent markers you can borrow for free.

I'll never forget a shift I had in Fantasyland at Magic Kingdom where there was a storm and guests flooded the store I worked at for ponchos.

A kids poncho is $10 and an adult poncho is $12 at the parks — with that said, I'll never buy one at Disney World.

Before my trip, I'll usually go to the dollar store and get a few cheap ponchos or bring a small umbrella.

There are tons of delicious treats you can buy at Disney, so a sugar-cookie kit that's been sitting in the Emporium gift shop for days isn't very appealing to me.

If I'm going to buy something sweet, I'll spend the money on a more original Disney treat, like Dole Whip.

Even if my shoes get wet, there's no way I'll spend $20 on flip-flops. Plus, as someone with large feet, I rarely even find my size on the shelves at Disney World.

Before my trip, I'll get a cheap pair from the dollar store or on sale at Old Navy.

I don't know about you, but I've never wanted to wear a heavy hat to Disney World with the scorching Florida heat.

That's why I'll never waste money on the bear hats they sell in Frontierland.

I think a Minnie Mouse headband or Mickey Mouse ears are a much more practical accessory in the Florida heat.

I'm an adult, and the Disney bubble wands cost $30, so maybe I'm just biased against this purchase. But even from what I've witnessed with kids in the park, the toy only really keeps them distracted for a few hours until they see the next light-up wand they want.

Plus, they can be super annoying for people around you at the parks (at least I think so).

If a bubble wand is the one thing that saves your child from having their 10th temper tantrum of the day, go for it. But I'll pass.

Having Chip 'n' Dale on your socks is cool when you're at Disney World. But I haven't found a use for them in the real world.

As a kid, I purchased my fair share of graphic socks to wear in the parks. Then they were just left to sit in my luggage until my next vacation.

At around $10 a pair, I'd rather spend that money on a shirt or piece of jewelry I'll wear year-round.

Inside the Trading Post in Frontierland, you'll find a big crate filled with rocks.

The kicker is they cost $6 each.

I'm not a rock person, but I'm still curious who comes to Disney World and spends money on expensive rocks when there are so many cooler souvenir options to choose from.