English Translation
I have to dress up.
se mettre sur son trente et un = to get all dressed up
être sur son trente et un = to be dressed up to the nines
© Larousse 2014
I have to dress up.
se mettre sur son trente et un = to get all dressed up
être sur son trente et un = to be dressed up to the nines
© Larousse 2014
trente-et-un because that’s the date for new years eve (12/31)
That will help me to remember it, thanks for that.