Simon Wheeler, the garrulous narrator of the story-within-a-story in Mark Twain's "The Celebrated Jumping Frog of Calaveras County," describes Jim Smiley as:
the curiosest man about always betting on anything that turned up you ever see, if he could get anybody to bet on the other side.
With this, he launches his long-winded account of the man whom the narrator of the frame story doesn't even want to know about.
The trait that made Jim Smiley such an anomaly—"the curiosest man"—was his addiction to gambling. Wheeler recounts Smiley placing bets on how long it would take a "straddle-bug" to reach its destination, which bird would fly from a perch first, and whether the minister's wife would recover from her illness. Smiley didn't much care which side he took in such contests, but he won more often than not.
Wheeler then goes on to describe in more detail Smiley's "fifteen-minute nag," which, despite its asthma, always finished a race a neck ahead of the next horse. Then Wheeler waxes eloquent (in his miner's dialect) about Smiley's bull-pup named Andrew Jackson—which didn't look like much of a fighter but could overpower any dog that had hind legs. Finally, Wheeler gets to the main story of his tale, which is about the frog named Dan'l Webster.
Wheeler could have (and would have) gone on and on about the unusual man, if the narrator hadn't made his escape at the first opportunity. But all his stories served to reinforce one idea about Jim Smiley: "He'd bet on any thing—the dangdest feller."