To make one's peni nut so hard they fucking die
Dude last night she totally mercy killed my wang it was crazy
by Bernutinmymouth September 14, 2017
1. euthanasia: the act of killing someone painlessly (especially someone suffering from an incurable illness)

2. Killing by one person of another who has an incurable illness or injury in its most painful stages.
My mom gave my grandpa a whole lot of pills and said it was ok because god doesn't punish mercy killing.