I stirred both mugs simultaneously with identical teaspoons briefly, and then simultaneously held the two spoons in a bottom corner of their respective mugs briefly, to essentially eliminate the swirling motion of the liquid in each.
12.
This'wastes'lift by lowering the pressure beneath and increasing it above-and the swirling motion caused by that air sneaking around where it's not wanted causes a spiral motion to get started in the air that swirls out behind the wingtip as a vortex.
