This true tid-bit I attribute to my dear father, Ben, known for his dead-pan dry humor. As a young boy, I was rocking rather enthusiastically on our great-big old rocking chair in our living room ajacent to our screened back door. Walking through, my dad stopped briefly and dryly admonished, " Don't rock too hard. You'll fall through the screen door and strain yourself." And promptly went along his way. Took me a while thereafter ( a couple of years ) to get it.
(From the "Rest" of RHF)