Like Cog, I am often annoyed by the biological realities of existence. If I could take a pill that would allow me to go without eating food for months on end, I would do that in a heartbeat. Having to sleep and go to bed every day also annoys me (I guess that's why I haven't had a healthy sleep cycle since I was in primary school).
Also, I sometimes have these momentary experiences where I suddenly become intensely aware of the fact that I am a bunch of biological material – fluids, muscle, bone, brain mass, etc, which at some point in the not-so-distant future will all disintegrate and become something other than me. It's a weird experience, man. Usually you're walking around thinking about more external, abstract stuff like: I have to do this and that at work tomorrow, I have to buy groceries, reply to a text message from someone, etc etc. And then suddenly BOOM – that moment of strange insight. And I'm not talking about that sort of objective reasoning about the human body that people do all the time; everyone understands on a theoretical level that they are biological stuff, but to really feel it, and fully grasp it – even for just a moment – that's something else.