1. Not being able to drink at company events :( Intern and team events are sometimes dinner, booze and music. My apple juice was pretty good, and if it when up the wrong pipe then I could get the burn too! (there was actually a time where I never experienced that and deliberately tried to to get a sugary beverage into my nose. Kids, right?)
2. Dodging the education question as long as possible. I once got past two interviews with Mozilla before they realized how old I was. If you tell them your age immediately, they stop taking you seriously. If you tell them after a few interviews it amplifies your interview performance.
3. Short summers. When I interned at Shopify, I only had two months. I did that twice, and that really shows today in my ability to ramp up on new jobs/projects.
4. Quietly laughing at how much money your friends think you make. My friends in high school estimated anywhere between 15 - 50 dollars per hour of income.
5. Constantly questioning whether you were a pity/charity hire. Didn't help that I'm also female. I think when I was hired at Shopify I may have been one of the poorest performing intern by whatever measure, but I ended up with a full-time offer in less than a year. Embrace and accept the brownie points you get just by being young!