Distraction is the 2nd upgrade on path 2 for the Ninja Monkey in BTD5. It costs $300 (Easy), $350 (Medium), $380 (Hard), and $420 (Impoppable). Some bloons struck by the Ninja's weapons will become distracted and move the wrong way temporarily after buying the upgrade. However, do not count on this to stop bloons from making it through. It is only a nice additional bonus, not something to be relied on. The Summon Whirlwind and Tempest Tornado upgrades for the Monkey Apprentice are much more efficient and reliable at sending bloons back to the start.
In BTD6, this upgrade makes a return. It is now the first Path 2 upgrade for the Ninja Monkey. Distraction can blowback bloons with a chance of 15%. It costs $300 (Easy), $350 (Medium), $380 (Hard), and $420 (Impoppable).
If this form of blowback is used on a Regrowth Bloon, unless there is a tower in range, it might regrow on the way back, which means if it is used on a Ceramic Bloon that has been destroyed, it could turn back into a Ceramic Bloon.