When you don’t know if it’s Saturday or Sunday after a night out. Also used by middle aged moms in an attempt to be hip while organizing a run.
“Man I don’t know if it’s Saturday or Sunday.”
“Dude it’s Saturunday”

Also,

“Mom calling the one time u jog a week Saturunday does not make it cool or trendy”
by Thattheregirl April 2, 2018
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When your Saturday turns into a Sunday
Saturunday
Saturday satur

Sunday unday
How was your weekend, did your Saturday turn into a Saturunday?
by Kalev Fitness July 12, 2021
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