The act of drinking Champagne on Thursdays as well as Fridays, and continuing to repeat the pattern and making it a weekly tradition.
"Good news, it's Champagne Thursday"
"But it's Friday"
"Uh, Yeah, I know. Thursday came twice this week."
"For the third straight week?"
"There's talk of making it permanent."
"Oh, kind of like Daylight Saving's Time?"
"Right, but for booze."