comfortable as an old shoe

(as) comfortable as an old shoe

Very familiar or comfortable, especially in an agreeably unpretentious or unrestrained manner. This car may have seen better years, but it's still comfortable as an old shoe to drive around in.
See also: comfortable, old, shoe
Farlex Dictionary of Idioms.

*comfortable as an old shoe

Cliché very comfortable; very comforting and familiar. (*Also: as ~.) My old house may seem small to you, but I think it's cozy. It's as comfortable as an old shoe.
See also: comfortable, old, shoe
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • (as) comfortable as an old shoe
  • comfortable
  • comfortable as an old shoe, as
  • an old shoe
  • all manner of
  • all manner of somebody/something
  • roar away
  • la
  • à la
  • with wild abandon