Perhaps inevitably, his interest originated in public school. A preoccupation with bowel movements is generally found among the very elderly or the well educated.
Every morning Johnny would quiz the assembled group on the results of their bathroom endeavours. Every morning I would refuse to answer on the grounds that I didn't know him well enough.
All that changed one day when the two of us were, appropriately, bringing up the rear. The stomach cramps which I'd been experiencing for the previous 40 mins could be ignored no longer.
"Quick! Hold my bike - I've got 30 seconds left!" I gasped, plunging down the hillside to be explosively, dramatically, ill.
Eventually, I got to my feet and climbed shakily, to the roadside.
"What a wonderful spot to choose, there was an eagle overhead," he happily exclaimed, before gathering together his toilet roll stash and proffering half to me, "Just in case."
"Johnny, tomorrow morning when you do your round-up...I think you know me well enough now," I conceded.