Colin KaepernickThe NFL has rules, and breaking those rules can come with a very hefty price tag.

San Francisco 49ers quarterback Colin Kaepernick was reminded of that this week when he was fined $10,000 by the NFL. The offense? Kaepernick wore Beats By Dre headphones — not NFL partner Bose headphones — to his postgame news conference.

You can debate the importance of such rule, but it’s a rule nonetheless, and it’s a rule Kaepernick broke.

Life in the NFL has many intricacies on and off the field, and dealing with the league’s supplemental discipline is something players must deal with on a weekly basis. In a post on FootballByFootball.com, three former NFL players recalled their experiences with that system — specificially fines handed out by the league.

Former quarterback Brady Quinn recalled a time in 2009 when he was fined for a hit on Baltimore Ravens linebacker Terrell Suggs. In the piece, Quinn insisted he didn’t mean to take out Suggs — with a hit that tore a ligament in the linebacker’s knee — but he knew he had to live with the consequences.

“Watching the play on film the next day, I felt sick,” Quinn wrote. “The video looked blatant and intentional, but I knew in my heart it was anything but.  I later received a fine for $10k.  I didn’t appeal.  I didn’t mean to do it, but the film told a different story.  What’s done had been done, and I couldn’t change a thing. ”

Then again, as former NFL linebacker and Football By Football founder Matt Chatham wrote, it’s not always that easy to accept a fine.

Click here to read more about NFL fines at FootballByFootball.com >>