Is it wrong to use "genocide" as a verb?

Solution 1:

If it's a large group you've killed, then 'massacred', 'slaughtered', or particularly 'exterminated' would work better. Genocide has no past tense as it's not a verb.

Solution 2:

Your friends are telling you that they'd rather you spared them the details of your quest to retrieve the Amulet of Yendor from the Mazes of Menace.

Genocide as a verb is Nethack jargon. By repudiating this usage of the word, they are showing you that they do not wish to be associated with the community of Nethack players.

In general English, while genocide does appear as a verb in print, it does not seem to have been accepted into the standard lexicon. And I hope it never will be -- I don't want to live in a world where we have a need for such a verb.