Humour is cruel by definition

[DanaC]

It isn't the level of cruelty...it's who is being cruel to whom. It's the power differential, or relationship between the person being cruel and the victim of that cruelty. It's the difference between a practical joke and bullying.

[Flint]

Originally Posted by DanaC

It's the difference between a practical joke and bullying.

The difference could also be in the set-up. It could, potentially, be funny to impulsively trip a co-worker as they walk by (with no pre-meditation); but if, instead, you had spent hours building a booby trap, only to film it knocking down a random passerby, then E (effort) would be greater then P (punchline) causing C (comedic index) to be negative. Also, in this case, the greater part of the joke is the creator of the set-up, not the victim; IE the creator becomes the subject. I should add that the very senselessness of the act could counter-intuitively have a positive, absurdist quality.