I'd always thought that the only reason for needing larger underpants would be because it made you fatter. Then again, I wonder if the research has found the Diet variety has the same effect on your dangly bits. That might explain a lot. I thought it was due to gravity and age. Something else to marvel at, together with my enormous...er, vocabulary.
Then again, what about the caffeine in tea and coffee? Does it all balance out? Is there a population of enormouse -ly fat laboratory mice out there somewhere pushing tiny wheelbarrows about with their (relatively) immense testicles loaded on them? All those tiny mouse farts and burps from drinking so much fizzy stuff. Perhaps the mice in the tea and coffee test laboratory look down on their cola drinking colleagues as being uncouth and uncultured while they wheel their own giant testicles about in their own tiny wheelbarrows. All that caffeine and testosterone must make for a lot of restlessness and mousey edginess. Are they breeding a new mouster race of killer mice? Perhaps this is what is needed to boost the Cola companies' shares.