you know what they say

you know what they say

Used to introduce and indicate the aptness of some well-worn cliché, maxim, adage, etc. Just tell me what's bothering you, honey. You know what they say—a problem shared is a problem halved. A: "I'm licensed and all, so I'm just going to represent myself. What's the problem?" B: "Well, you know what they say—an attorney who represents himself has a fool for a client."
See also: know, say, what
Farlex Dictionary of Idioms.
See also:
  • the British are coming
  • (good) black don't crack
  • computer says no
  • X's and Y's and Z's, oh my!
  • Don’t call us, we’ll call you
  • don't call us, we'll call you
  • Don't call us, we'll call you.
  • Don't ring us, we'll ring you.
  • ye olde
  • Eskimo(s) have (some amount of) words for snow