Sure, when my organs fail me, I can use myself as spare parts.

No rejection tissue for me!
On a less creepy note, I would get bored with myself after several matches of Street Fighter and Killzone 2, doing the same tactics as each other. That's when I break out the lightsaber and behead myself.
Edit: ... Wait, then he would do the same thing and possibly block it. Then we would fight doing the same tactics, and attacks... over... and... over... OP you have angered me by causing this paradox of thoughts. To quote Liam Neeson,
I will find you, and I will kill you.