A little bit like an advanced-level moon
, whereby the person doing the spreading drops his or her kecks and gently pulls apart their buttocks, exposing their anus
to shocked onlookers.
I'm telling you, it was rank. There we were in McD's, and in came Matt Buckley and dropped his pants, pulling a spreader at us. Two things became obvious - 1, that he'd recently eaten sweetcorn, and 2, that he needed to practice wiping a bit more thoroughly.