Jordon Hudson proved she celebrates "Mean Girls" Day ... as she showed up to support her man Bill Belichick at Chapel Hill wearing a pink satin two-piece.

Accessorizing with her trademark football-shaped purse ... Jordon also wore a championship ring on her finger Saturday and a pink bustier top and matching pants that we think Regina George would approve of.

Looks like we'll have to change the iconic "Mean Girls" phrase "on Wednesdays, we wear pink" to include Saturdays, too!

Jordon was on the sidelines to root Bill and the University of North Carolina football team on as they faced off against the Notre Dame Fighting Irish.

Unfortunately for Bill, Jordon and the Tar Heels ... the Fighting Irish came back from being down early to beat UNC 37-26.

There's still plenty of the season left -- more than enough time to turn their 2-2 record around. Their limit does not exist!

The team has faced a few controversies lately ... the program's general manager, Michael Lombardi, resigned last month ... and the program is being investigated after accusations of sexual misconduct and drug use.