your Sunday best

(one's) Sunday best

One's very best clothes, as one would wear to a Sunday church service. Instead of some big party, let's all get dressed up in our Sunday best and go for lunch at a fancy restaurant for my birthday! This is going to be a formal event, so please come dressed in your Sunday best.
See also: Sunday
Farlex Dictionary of Idioms.

your Sunday ˈbest

(informal, humorous) your best clothes: She got all dressed up in her Sunday best to meet her boyfriend’s parents.
See also: Sunday
Farlex Partner Idioms Dictionary
See also:
  • (one's) Sunday best
  • get into (one's) Sunday best
  • Sunday best
  • in (one's) Sunday best
  • in Sunday best
  • be in (one's) Sunday best
  • best do
  • (had) best (do something)
  • as best (one) can
  • as best one can
References in periodicals archive
It's Scotland's paper and your Sunday best, every week of the year.
Plus all the latest news, sport and features that have made the Mercury your Sunday best.
I can see that you're all green with envy I can almost hear all of your snarls `Cos I've been invited to the wedding of the year The wedding of Camilla and Charles My invitation arrived just a week ago Complete with the Royal family crest With a message inside that read Hey, Bob, Be my best man, but come down in your Sunday best I'll sit in the front row of the GuildhallRubbing shoulders on Charlie's right side And I'll have the ring in my back pocket For our Charlie to give to the brideI suppose one or two won't know me They'll wonder just who I am And if I get some real nasty glances I'll refer them to our Charlie's mamThen when we stand on the steps of the Guildhall I'll know that I've done a great job But lots of people will surely be asking Hey!
The experience was akin to dressing up in your Sunday best only to find your favorite church with defaced frescoes, overturned pews, and the central air turned down to 60 degrees.
jSo why not go and enjoy some real, live football - courtesy of Oldham Athletic FC and your Sunday best sports paper, The SP.
So to readers old and new: Thank you for making us your Sunday best. *Based on industry sales estimate.
Stick with the Sunday Mirror: We're your Sunday best.