a slippery slope
A situation in which some behavior or action will eventually lead to a worse form of the same behavior or action, or a disastrous outcome. Eating that piece of cake is a slippery slope that could lead to you completely abandoning your diet. Verbal abuse is often a slippery slope that leads to physical abuse.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a slippery slope
COMMON A slippery slope is a course of action which is likely to lead to failure or serious trouble. It's a slippery slope. You give in to one demand and soon find that you're doing exactly what they want. The company started down the slippery slope of believing that they knew better than the customer, with the inevitable disastrous results. Note: You can also say that someone is on a slippery slope or on the slippery slope. These young people may already be on the slippery slope to criminality.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
slippery slope, a
A dangerous path or situation leading to disaster. Alluding to a path down which one could slide to a bad fall, this figure of speech dates from the mid-1900s. The Daily Telegraph of January 6, 1964 stated, “While Western feet thus approach what some fear may be a slippery slope towards recognition of the East, Ulbricht’s ground seems as firm as ever it was.” In a New Yorker piece about writers chronicling Sherlock Holmes, one of them is quoted as saying, “I’ve now done . . . more than fifteen hundred pages and I’ve only gotten up to 1950. It’s been a slippery slope into madness and obsession” (Dec. 13, 2004).
See also: slippery
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer