When it's midnight and you are talking about the day you just spent, and get it confused with the day before because it's past midnight and your mind is technically set on the next day, though you didn't sleep yet.
The term “Yestoday” is defined as today and yesterday combined. It shows two specific time periods and events that can happen during both times or having two days combined into one term.
During Prohibition, many bootleggers would discreetly refer to da previous day of moonshinin' as "yeasterday" when da "revenooers" were within earshot.
A concatenation of "yesterday," "today" and "tomorrow," indicating a specific period of time where it's so late that it's technically the next day (past midnight) but in your head it's still "today" even though you're discussing (technically) yesterday.
Guy: I remember discussing it yestdayrow with Charlotte.
Girl: Which yestdayrow?
Guy: The one that just passed...
Girl: Ohh...