My poos also do not take very long most of the time, so I don't always read, but if my stomach is a bit unhappy and it might take some time for the whole thing to be done, I read. I also think and muse on various things. Sometimes I get embarrassed imagining fictional situations because suddenly I'll feel all the people in my head are watching me poo.
My friend once said this: "I love pooing. Sat on the toilet is the only time in the world where no one expects anything of you."
I think it has truth. :D