BT Šab 129b(32) :יומא דהוו מיפגרי רבנן הוו אמרי האידנא יומא דשפמי הוא‏ : when the rabbis were taking a day off they would say: "today is the 'day of the upper lips' [i.e. a day of no profit]"
See the entire entry for spm n.m. upper lip

BT Šab 129b(32) : יומא דהוו מיפגרי רבנן‏ : when the teachers were taking time off
See the entire entry for pgr#3 vb. C to be idle