[RussEfarmer]

This is called bunnyhopping, it lets you use something in the game engine called air strafing (the "force" that lets you turn while you are in the air) to gain speed and preserve it through multiple jumps by jumping the exact moment you touch the ground. MiniMe happens to be very good at it.

You can do this on any server, but it's hard. It is significantly easier to gain high speed with it in our server because sv_airaccelerate (sort of a multiplier for how "tight" you can move in the air) is set to an excessively high value of 1000 as I explained in this thread.

The jump pack makes bunnyhopping a little bit easier but it doesn't really make a difference with bunnyhopping.