Growing Up Fast

 is a Fallout 3 quest. As part of this quest, you also gain the Vault 101 Citizenship Award achievement.

Have a present
This quest begins immediately after the Baby Steps quest, though it occurs about nine years later, at your 10th birthday party. You'll be congratulated and given your Pip-Boy 3000.

Enjoy your party
Enjoy the party and speak with your guests.

Walk forward a bit and you'll be greeted by Amata. This is your first real conversation, and you're given three possible responses. No matter which one you pick Amata will tell you to guess what she got you. In the end she gives you the comic "Grognak the Barbarian #14."

Turn right and talk to Old Lady Palmer and she'll give you a sweetroll.

Turn around to see a Mr. Handy named Andy try to cut the cake, but accidently destroys it instead. This will agitate Butch DeLoria, and he will demand your sweetroll. If you've already eaten your sweetroll, or if you refuse to give it to him, Butch will attack you. If he does, Officer Gomez will break the fight, and you have the option of telling him what happened.

Amata will approach you when you're done dealing with Butch, and you can give her three different responses.

Walk past your Dad (whom you may inform of what had just transpired) and talk to Stanley - he'll give you a baseball cap.

Your Dad will get up and go to the Intercom that's just started beeping. He'll tell you head down to the reactor room for a surprise he and Jonas have been working on. As you head towards the cafeteria exit, Beatrice will walk in and hand you a poem she wrote for your birthday.

Armed and in Charge
Your new objective is to meet Jonas in the reactor room. Head out the door your Dad just opened and turn right; you should bump into Beatrice on your way out. If you wait around after your Dad opens the door, Beatrice will walk in and talk to you. She'll give you a poem which you can read in your Pip-Boy 3000.

Turn left at the "reactor" sign head down the hall and turn right. Go down the stairs and enter the room. Talk to Jonas and wait for your Dad. When he arrives, he'll give you a BB gun. Follow him through the door. You'll be given a new objective. Shoot all 3 targets with the BB gun. This is pretty straightforward.

After you shoot each target once, you'll be charged with a new task: Kill the radroach. No real threat here, as a few well-aimed shots should kill it quickly. To celebrate this, your Dad wants to take a picture with you. Stand beside your Dad to complete the quest.

Trivia
The sweetroll and the scenario of a bully trying to take it from you is recurring event during the tutorial/character creation sequence of Bethesda's Elder Scrolls games.