when two Sundays come together

when two Sundays come together

Never. Usually said sarcastically. A: "When are you going to help me clean out the garage?" B: "How about when two Sundays come together?"
See also: come, Sundays, together, two
Farlex Dictionary of Idioms.
See also:
  • (one) will be lucky
  • (one) would be lucky
  • (I) would if I could
  • be big of (one)
  • (one) should be so lucky
  • (well,) I never!
  • a bright spark
  • couldn't happen to a nicer (person)
  • twenty-twenty hindsight, with
  • a (real) winner