My drivers licence.
And if you didn’t, I did.
My first ever really for real paycheck went as a deposit for my Sega Dreamcast. From Electronics Boutique. The store that was paying me to sell Dreamcasts at the time. It’s all circular, man.
And, I took my Uni friends out to dinner, as was traditional. Luckily there were only four of us… it was not the world’s largest paycheck.
An “Advance” digital watch. I couldn’t afford an Armitron. It had an alarm AND and stopwatch. Ooooooooo. That was 1979.
I was 15. Probably gas.
I don’t remember what I did with the rest of it, but I do remember that I spent part of my first cheque from my first “real” job (i.e. not babysitting) when I was sixteen on taking my parents out to dinner. I remember feeling quite proud that day.
See **Mr Bus Guy’s ** answer. Then probably weed.
With my babysitting money (I started babysitting when I was 11) I bought riding lessons. I later worked at the barn in exchange for lessons (that beat babysitting by a long shot!)
With my paycheck from my first real job I bought a leather coat and a boombox.
See silenus’s answer.
And on further review, probably we should reverse the order.
Some of it went for room and board to my parents. Some went in the bank. The rest I used to buy one pair of sturdy round-toed blocky heeled fabric covered black high heels, and one pair of pointy toed strappy black patent leather stilletos.
Ahhh. I guess I’m more of a shoe person than I thought.
Nearly 20 years ago, I got my first “real” job working full time at a doctor’s office as a medical assistant. With my first paycheck, I got a divorce. (It was a $29 Do-it-Yourself divorce, plus the nearly $100 filing fee.)
Best $29 I ever spent.
I got my first real paycheck during the summer of 2000 for programming work. I went on a holiday to London with my closest friend and I met my future wife in the hostel we were staying! The interesting bit is that I got my check slightly late, and if I didn’t get it by that day, my friend would have joined a friend of his to go to Spain, I would not have gone to London and so would probably be alone.
So the net result of my first paycheck was that I met my partner. Not bad at all! 
I was 15, and just completed my first week of work in my summer job, dipping ice cream at the Polar Bear Ice Cream Shop in Gun Barrel City, Texas. I spent something like $20 on a ticket to the very first Texas Jam at the Cotton Bowl in Dallas.
As far as my first (real) job out of college, the first thing I did was drive down to Birmingham, AL (I lived in Huntsville at the time) to the nearest Rickenbacker dealer and ordered a JetGlo Rickenbacker 330, which I still have, almost 21 years later… 
I don’t remember what I bought from the paycheck from my first job at the movie theater. But I do remember after getting my first “adult” job out of college I bought one of those “home theater in a box” kits with 5 speakers, sub, and receiver. That was about 6 years ago, I guess.
I sold it during my unemployed days so I could pay rent. Good times.
With my first paycheck ever I bought the cutest shirt with the Cat in the Hat on it. That was in high school. With my first college paycheck I bought my first ever game console, an N64. (I wasn’t allowed to have any game consoles as a child because they weren’t sufficiently educational.)
Knowing me, Yu-Gi-Oh cards.
Now if only I could get some of that money back…
A RadioShack MC-10… I am such a nerd.
I was 18. I bought dinner for my ex husband (we had just started dating - BOY do I wish I knew then what I know now!) and a few of his friends at Friendly’s at Orland Park Mall.
Been paying for it ever since… 
Knee high black high-heeled boots that laced up the back. I was 15. I’ve always been a shoe whore.
My first paycheck? I was 15 years old, I worked for an old man and we mowed lawns during the day and cleaned office buildings at night. I was a janitor I reckon. My first week I recieved a check for 50 dollars! Mom took me down to Crawfords food market and we cashed the check at the courtesy booth. On the way out of the store I asked her to wait a sec and I broke a 10 dollar bill to buy a candy bar. An almond joy. It cost a dime. All the rest of the candy bars were a nickle, BUT what the hell I was rich! AND I needed jinglin money!
The next summer and after school I worked at a bowling alley.It was probably what I consider my first REAL job. Saved all my money and bought the family car. Dad wanted to trade it in and I offered him 800 dollars cash and he took it. '61 chevvy bel air, this was in '68 and I was crappin in TALL cotton my senior year! Hell I had an almost NEW car! I also met my wife at the same time. DANG I wish I still had that car!
The wife? Yeah I did go ahead and keep her!