The line belongs to The Notorious Frog of Calaveras County, a short story written by Mark Twain. It narrates the story of a guy that narrates another story (called <em>a frame story</em>) about a guy that used to bet on everything. The person described in the story takes his actions (betting) to a point where he puts his money on a frog that had been manipulated before the bet. With this phrase, the speaker wants to express that the guy was totally a gambler.
