Actually, I'll amend. I'll just lock you in a room with my mother for 3 days. The woman will talk you to death. And if by chance she doesn't talk you to death, you will kill yourself just so that you don't have to listen to her for another minute.
I think one of the more venomous cone snails would be a good weapon for the requirements of this scenario. The fact that it's in a shell makes it relatively easy to handle as a weapon without getting stung, compared to most poisonous animals (although some care is still required). All it would take is to get close enough to you without you getting particularly suspicious, and then quickly hold the shell opening against any part of you and give it a little shake (it doesn't need bare flesh, its stinger can easily penetrate clothing). The toxins take a little time to act (maybe an hour or so), but there's no antivirus.