There's nothing like a little good-natured and good-humored pranking. The fine art of subtlety f*cking with someone in ways they don't even immediately realize is a truly fantastic skill.
These days 'pranking' and 'trolling' are often too crass and violent, without any regard for the subtlety that makes the payoff great. Some Youtubers need to learn that assault is not a 'prank'.
These hilarious trolls are doing it right and messing with the minds of those around them in the best possible way.