Knifey

A person which tends to choose aggressive options in order to reach a certain goal and clearly choosing this path just to save time. Possible scenarios could be within a videogame; A passive guardian is standing before a bridge and you need to fulfill a certain quest so that the guardian allows you to cross it. You could do that lengthy quest or be "knifey" and just kill that guardian because it might be quicker. In this example, you witness a "kniefy" player.

Friend A: "Okay, lets do this sidequest so we can cross the bridge."
Friend B: "Nah, let´s just kill this guardian quick."
Friend A: "Bee, don´t be so knifey again."