I'm a big fan of Billy DeBeck's great comic strip, Barney Google (if you're not familiar with it, I recommend you check it out)... but DeBeck did a one-panel gag feature for a while as well, called Bughouse Fables. The central conceit was that the scenario would be something wildly unlikely, something only a lunatic could actually think might happen (hence the name - "Bughouse" being contemporary slang for an insane asylum). Here are a few examples from between 1921 and 1926, dug up from online newspaper archives with the help of Charles Thompson (thanks Charlie!) and other old-time strip afficionados of my virtual acquaintance, heroes all.
You'll notice the very last one here is by a hand other than DeBeck's - a bit of research leads me to believe that it's by Paul Fung (big F, small U, small N, small G), who was DeBeck's assistant, and who took the panel over eventually.