The ability to control one's bladder isn't just handy in all situations like when facing a malfunctioning commode or a stalled subway ride. It's also apparently a way of life. Greater levels of bladder control result in an increasing ability to resist the urge to spend money, say a group of academics in Norway. "Inhibitory spillover" refers to the idea that one's ability to control one type of urge -- like having to pee -- can carry over to other aspects of life, including thriftiness [source: Tuk, et al].
In other words, if the thought of a liquid substance spilling makes you want to run to the nearest restroom, you may be a compulsive spender.