Yea, not so funny, the old joke may have some truth to it I don't know. But aren't we all that quivering wet poodle riding the glass turntable? It's all flying right through us; radio, microwave, TV, WiFi, satellite data, to say nothing of background frequencies from exploding stars, white dwarfs, and your neighbors remote controlled drone looking in your bedroom window, e-gads, were all in a microwave on "thaw" cycle.
Duke University, may their basketball team forever have sore feet and blurry vision, just came up with a panel, a bit like a solar panel, to harvest all these errant transmissions and convert it to energy. In a few years we may have a funny looking little white card standing on the shelf and cabled to the cell phone or computer charging the dickens out of it. The tin foil hat guys were right all along, but rather than shooting up the mall over it, maybe we buy a little card that will snatch free power out of thin air 24 7.