When a two-stroke engine idles or warms up for an extended period of time (sitting at a red light, initial start-up, etc...) it doesn't burn all the two stroke oil in the gas. Instead, the oil collects in the exhaust pipe and in the cylinder/on the spark plug. All that oil needs to go away before riding the moped, or else there will be little to no power, and it will die out and foul the spark plug.
To get rid of all that oil, you will need to “clear it out” by revving the engine up and blowing out all the oil that has settled in the pipe/cylinder. When you do this, there should be a ton of blue smoke exiting the pipe throughout the RPM range. When doing this, be sure to do 1 big rev by slowly revving it faster and faster, holding the throttle open until you can hear the stuttering bogging sound go away and a nice throaty powerful clear sound.
This is seen a lot in races where people are constantly revving their two stroke bikes. The purpose is to keep the cylinders/pipe “cleared out” of oil so they can have full power without bogging.