With those type of travel you can't help but get to know the people you are travelling with really well as you are living with them 24/7 and tend to do most things as a group - if nothing else there is just a lot of time for talking.
One topic of conversation which occurs with a fair amount of regularity, if you'll excuse they pun, is bowl movements. The health of your fellow travellers guts is of acute interest and it is perfectly normal to ask how someone's guts are doing, especially - as with last night - if you ate somewhere very local (we did - a tiny little hole in the wall type place, where the food & beer was cheap, plentiful and tasty) or ate something unusual (we did - bulls testicles, which are bland) or to discuss when someone isn't doing so well and how we, the group, can help them (if nothing else when you get hit hard with Deli Belly it's good to have a few people who'll get stuff from the shops for you, something which is less likely to occur whenever independently backpacking).
Not something which is normally discussed much at home.
