4 nerdy costumes you can wear this Halloween from stuff you already have

There's nothing like expecting to not get invited to anything for Halloween only to get an invite to a sweet party at the last second because someone cooler than you couldn't make it. Not that I would have any personal experience with pity invites...

Of course, the challenge is pulling together a top-notch costume at the last-minute. And, being the nerd that you are, you need to show come up with something that will keep your nerd-cred solid in the public sphere.

These costumes are easy to put together even on the shortest of notices, and will ensure no one questions your authority on things like parsecs and video games. We're making the assumption that you have a few Halloween things packed away from previous costumes, meaning you can put these together with what you already have or just a few easy items that don't require fighting off all the other last-second Halloween shoppers.

Here are four nerdy af Halloween costumes you can throw together at the last minute:

Doctor Who

Matt Smith as Doctor Who.
Copyright by BBC and other respective production studios and distributors. Intended for editorial use only.

It's pretty simple, really, since the Doctor can pretty much be, well, anyone, technically.

All you really need is a trench coat—or a sport coat like Matt Smith's above—and ideally a bowtie. Even though not every doctor wears a bowtie, it will be the key signal to your fellow partygoers that you are who you say are, a bad A time lord to be precise.

You'll also need to equip yourself with a sonic screwdriver. Again, there's a lot of flexibility here. Heck, you could even just carry a screwdriver around and wave at things in a worst-case scenario. You can also easily fashion one out of some cardboard, markers and duct tape. Seriously, you just need something that vaguely resembles the gadget and you'll be good to go.

Oh, and of course you'll need to act the part by constantly being on the lookout for Daleks.

A zombie

Whether you're a Walking Dead fanatic or more of a George Romero fan, it's really tough to get more Halloween than zombies. It's also one of the easiest costumes to throw together in a pinch, especially if you have some green makeup lying around from last year.

Just find an old shirt and pair of jeans you don't care about, and get to ripping. Boom, you're halfway there already. If you don't have fake blood to splatter on your clothes and around your mouth (because, duh, you eat brains), you can use corn syrup, chocolate syrup and red food coloring to make your own.

Adding some green makeup to your skin to represent decomposition can add a nice effect as well, but it's not necessary. What is needed is the perfect zombie walk: head tilted to the left, arms straight out, feet shuffling, and mumbling "braaaaaaiiiinnns".

A nerd

Well, there's not much nerdier of a Halloween costume than just a nerd. And considering you're on a site called Classic Nerd, chances are you've got the goods in your closet to make this one happen.

All you need are glasses (real or fake), a button-up shirt with a pocket, any pants you can reasonably pull up high without hurting yourself, and some masking tape.

If you don't have glasses, you can make a quick run to the dollar store or a local Walgreen's and grab a pair of cheap reading glasses. Pop the lenses out and you're good to go.

Be sure to pull your pants up as high as you can, or use pants that are a bit too short for your legs to get that classic nerdy highwater look.

Whether you have a pocket protecter or not, neatly arrange a few pens in your shirt pocket, and offer them to fellow partygoers whenever you have the chance.

Now, take  a little bit of masking tape and wrap it around the center of your glasses—because nerds are constantly having to fix their glasses for various reasons, as we all know.

Finally, memorize pi to at least 10 places. Here's a little help: 3.1415926535.

Waldo

Those glasses you just splurged on at the dollar store are about to come in handy once more. And the only other things you'll need are a striped hat and striped sweater—red and white of course.

You can hit up a thrift store if you don't have something that works off the shelf, or just find a white knitted hat and long-sleeve shirt and color in the red stripes yourself. It really doesn't even have to look that perfect for everyone to know who you are and get the joke.

And obviously you'll also need to spend the evening subtly blending in.

More from Classic Nerd: