Rat Pack | rat | The Rat Pack | Rat | Strong Poison | Roland Rat | Poison Ivy | Poison Idea | Blek le Rat | The Rat Pack (film) | poison oak | Poison Ivy (comics) | Eisentraut's brush-furred rat | Your Friend the Rat | The Rat Patrol | Rat Scabies | Rat running | Pretty Poison | poison ivy | The Poison Sky | Season of Poison | Rat (zodiac) | Rat Genome Database | Rat-baiting | Poison's Greatest Hits: 1986–1996 | Poison Ivy (1985 TV-movie) | Naked mole rat | Flores Cave Rat | Ciske de Rat | Another Man's Poison |
One possible origin is the way that a rat is attracted to rat poison like a child to candy, another possibility being the use of actual candy, particularly chocolate, as bait when luring a rat into a trap that will lead to its imprisonment or demise.
Another variation of this puzzle appears in The Simpsons, season 20 episode 13 (Gone Maggie Gone), where Homer has to get across a river with Maggie, Santa's Little Helper, and a jar of rat poison (that looks like candy).