The rocket chair is very fast as compared to the normal chair. You will need to give two rockets to Nerdy Nathan in order to get the rocket chair. Go through the guide and follow the instructions to get the rocket chair.
First, you will need to talk with Nerdy Nathan.
And then you have to find 2 Rockets and give them to Nerdy Nathan. Come to this location to get them.
After getting the Two Rockets, Talk to Nerdy Nathan to get the Rocket Chair and Badge.
The Rocket Chair is faster than a Normal Chair.
You will sadly lose it after the Vents Scene in the Main Ending or the Detention Scene in Karen Ending.