To perform this glitch, deploy a Regenerator right before jumping onto the Man Cannon. As you are propelled through the air with the Regenerator, you will stop in midair (the sound file of a Man Cannon would play at this moment) and you will be propelled back to the original launch area. In most cases, players who move a bit will not reach their launch area, instead falling to their death. You can also do this glitch in Matchmaking.
If propelled back, you can easily lead a pursuer to believe you are traveling to the other side and then change direction mid-flight. However, there is a high chance of mere falling which makes this impractical in a real combat scenario.