Re: Ah well...
"force-feeding bananas "
A tiny amount of phenolphthalein on the water would have a more decisive effect.
Just don't overdo it. My chemistry teacher at high school claimed that when _he_ was a lad someone doctored the teachers staffroom coffee urn one lunchtime, resulting in virtually the entire staff spending all afternoon in the karzis and some needing several days off.
(This was the same chemistry teacher who blew a hole in the bottom of the school swimming pool whilst demonstrating the explosive properties of "around a pound" of sodium wrapped in newspaper....)