When a friend had me over, but had to step out on his own for a bit, I was left alone in his apartment for about a half an hour.
That was months ago, and he is still finding eyes on things.
The secret: I have also given agents in his area sticky eyes to put on things. He recently found eyes on the bottom of his toilet seat, and he actually believed I put them there. He was impressed, and wants me to die so much now.