Never in your schooling were you taught about the trials and tribulations of adulthood.
Sure, you may have heard subtle whispers and warnings sprinkled throughout your childhood, but you often brushed them off as you frolicked in the waters of your youth.
But the warning signs were there. They were planted in ageless classics, such as "Billy Madison."
Suddenly, Adam Sandler's philosophical predictions matched up to Machiavelli's ingenuity. As they're blaring in your mind, you can't help but remember these wise words: "Stay (in school) as long as you can."
Now, the youthful world rejects you. You've been kicked to the curb, and left standing beside a pile of responsibilities and broken dreams.
Here are nine ways you'll know you've crossed over to the desolate land of adulthood. There's no turning back now:
1. You drive by college campuses and cry.
Look at them, those young scholars. They have no idea the train of life is about to crash at the speed of reality.
You used to be one of those people who was only concerned about finals and night life.
You can't help but break into a fit of tears each time you see college students basking in the sun, reading books that will never help them once they graduate.
2. You check WebMD more than you check Facebook.
In your younger days, when you were unable to sleep, you might have rolled over to check Facebook or Instagram (or anything else) to help you fall back to sleep.
Well, my aging friend, that's all changed. Now, the fear of life has crept inside you and infected you with the idea that no one is going to look after you but yourself.
Can't sleep? Something is clearly wrong with you. You'd better check WebMD to be sure.
Look at that. You've diagnosed yourself with fibromyalgia.
Welcome to the world of adulthood.
3. Instead of the boogeyman, the loan man haunts your dreams.
As a child, the boogeyman was often found lurking under your bed or in your closet. Now, as an adult, it's the loan man that not only follows you everywhere you go, he also haunts your dreams.
You wake up in a blanket of sweat, with the image of the loan man lighting your pile of money on fire while dancing on the ashes. It's the cold truth no college wishes to share.
4. Hangovers last a week.
Instead of going to a friend's house to pregame, you decide to get wild and crazy by bringing a bottle of wine to your book club. Before you know it, you've had three glasses of wine, and must force yourself to climb into an Uber.
No longer will you wake up bright-eyed and bushy-tailed in the morning. Oh no. Hangovers that used to last 30 minutes to eight hours now last you days.
When that EDM car commercial comes on TV, you have a sliver of hope that one day, you'll be able to rally like you used to. But the sad truth is, that beer will send you to your grave.
You've been warned.
5. Nothing makes you happier than going to bed before 10 pm.
Do you remember when you used to go out at 10 pm? What a monstrosity.
Nowadays, nothing makes you happier than the thought of crawling into your bed before 10 pm and reading a book. Sometimes, you might spice it up with a little visit from your friend, Netflix.
It's a simple aging life, but a good one.
6. You spend more time at the grocery store than the night club.
From the time you wake up -- until you drag your feet to the grocery store -- you're actually forced to think about sustenance. It's no longer put in front of you like you're a pampered house cat. You'll literally die if you don't feed yourself.
Therefore, you spend more time at the grocery store. You plan your meals for the next week like a responsible adult, as opposed to making it rain on your bar tab.
7. Your 401(k) becomes a frequent topic of discussion.
Imagine: You're with your group of friends, chatting away about the hills and valleys of life, when the conversation switches to finances. The crazy thing is, you can actually contribute to this conversation.
In fact, you're secretly hoping someone will bring up credit scores, just so you can subtly slip in the fact that yours went up two points.
Who are you? Not a young person, I'll tell you that.
8. Your paychecks go to non-materialistic things.
You know you're officially an adult when getting paid is the equivalent of setting your paycheck on fire.
Will you ever see that money? No. All your money goes to bills, silly.
You might get lucky with a few dollars to spare and find yourself splurging on oil changes, insurance or new tires.
Want to drop some G's on clothes? That's cute. But it's not happening.
9. Your metabolism hates you.
After you turn 26 — in fact, the day after your 26th birthday — your metabolism turns against you. Remember the days of bathing in McDonald's grease? Well, that one pink Starburst is going to cost you a four-mile run.
Suddenly, you'll be ogling at pictures of your 21-year-old self. Why did you take all those Chipotle burritos for granted?