Alright I have some methods number 1:
Alright first invite the person to watch a movie or something choose a move and say your gonna get some soda so get some Mountain Dew put fairy soap in the persons drink make sure to put a deadly amount of it mabye add some rat poison or normal poison if you have in not to much to notice that there’s soap in it. Now grab a Mountain Dew for yourself and give the poisoned drink to the person and say let’s do a chug battle to the person and they will probably accept and you will successfully killed someone (not full proof doe and if you don’t have fairy soap just get other soap that’s also green)