Piss & feces. Probably some semen, and vomit too. Oh and of course, pubes & arsehair. And paper, how could I forget? Some of that paper contained snot too, so yeah that goes as well. And blood, duh. I reckon not everything I've swallowed has been thoroughly digested either (I've lived just over 18 years, that's a few thousand meals and I admit, my intestines aren't perfect) so a few kinds of food & other edibles (and non-edibles, we've all been kids).