The Thursday preceding a holiday that falls on a Friday. Not to be confused with ThuFri. Term applies when the Friday is a company paid day off or a day off from school.
Thursfriday is a Thursday before a holiday Friday; a Thursday that feels like a Friday because it is the last work day of the week (e.g. the Thursday before Good Friday is a Thusfriday).
Going out on a Thursday, Friday and Saturday night in the same week and getting completed hammered each night.
The feeling on a Sunday after a thurfrisat can be called the thurfrisatshit
"you fancy doing a thurfrisat this week?"
"I would do, but I canny afford it"
"that thurfrisat we did was mental, i've got well bad thurfrisatshit today"