Well there's always a moment in everyone's life where he or she will have to end somthings life.  There are many different situations that involve different methods and so forth.  Since I am mainly refering to bugs or small animals some examples can include:

Those little small stupid waste of life bugs like gnats that when you slap them dead its just funny to smear their inferior amount of guts across the suface you killed it on.

Then there are those bigger bugs like big spiders and big flies that you can easily step on having a feeling of great supieriority being above them on the food chain but if you pull out a tissue and you feel that crunch its a whole new ballgame.  Also you can just flush them down a toilet and laugh as they spiral to a hopefully slow death by drowing in a smelly liquid form of human feces.

Next their are little creatures like tiny lizard you find in the woods.  For instance one time when I was camping I "accidently" dropped a salamander into a fire and I thought it was going to slowly burn as it fought for its life but on the contrary it just filled up with air and popped a couple of seconds later which was very cool.

Also theres those pain in the ass squirels and racoons that are everywhere and those its just necessary to bust out a pellet gun or a paintball gun and shoot them until they run a away limping and you have the knowledge that they will starve to death becuase they cant get food with a messed up leg or they'll just fall from the tree or whatever and die right there.  Either way its a big relief.

Finally theres animals that you hunt like deer, turkey, and babies but those topics are open for discussion from everyone's own personality.