{adv. phr.} Regularly; consistently; all the time; always. * /He plays good tennis day in and day out./ - Also used with several other time words in place of day: week, month, year. * /Every summer, year in, year out, the ice cream man comes back to the park./
DAY IN
Meaning of DAY IN in English
Slang English vocab. Английский сленговый словарь. 2012