On a segment from the PBS show of my childhood, “Square One”, a wrestler is challenged to weigh a dog. He captures the dog and puts him on a scale, but the dog keeps jumping off before the wrestler can get his measurement. The solution, whose cleverness so overwhelmed me I repeated it to my parents during dinner several times, was to weigh himself, pick up the dog, weigh himself and the dog together, and subtract his weight to get the dog’s weight.
I tried to emulate the technique by weighing such things as my Fisher Price Wild West Saloon, but pretty much everything I could pick up and carry around with me at that age weighed less than a pound, and the effort failed. Also, I just now realized for the first time it wasn’t actually a wrestler in that show, but a grown up pretending to be one. Damn.
Here’s a variation on that old theme. You’re at the gym when you notice a cute guy/girl bouncing on an exercise ball (pilates ball, big round blue thing, whatever it’s called). You want to figure out how much they weigh, because your bunk bed has a certain tolerance you can’t exceed. It would be impolitic to ask directly what they weigh, and you’re unlikely to pick them up and carry them to the scale in the locker room. Still, by observing them for a short while, and a bit of experimentation, you can figure it out. How?