San Francisco 49ers tight George Kittle's decision to wear a shirt saying ‘F**k Dallas' under his jersey during his team's Week 5 win over the Cowboys proved to be a costly one. Kittle was fined $13,699 on Friday “for use of abusive language” on the shirt, a league source told Jeremy Fowler of ESPN.

Kittle, who torched the Cowboys defense for three touchdowns on Sunday Night Football this past week, posted a picture of himself lifting up his jersey to reveal the shirt on his Instagram account the following morning.

Not only did Kittle's NSFW Dallas shirt garner quite a few laughs from NFL fans, but it also intensified a 49ers-Cowboys rivalry that was already a bit testy to begin with.

George Kittle's shirt spurs 49ers-Cowboys trash talk

Cowboys star pass rusher Micah Parsons got wind of Kittle's shirt later in the day this past Monday and fired a response at the 49ers tight end on his show, The Edge with Micah Parsons.

Parsons told Kittle to “laugh now, cry later”, adding that the 49ers tight end made it “personal.” The Cowboys Pro Bowler promised that his team would “have something” for Kittle and his squad should the two meet again in the postseason.

Then, 49ers star Deebo Samuel clapped back at Parsons, repeating the 42-10 final score of the Week 5 game while insisting that Dallas does not want to see San Francisco again this year.

Kittle clearly created a firestorm with the shirt. But he doesn't regret it.

George Kittle comments on Dallas shirt

Kittle said that he would “do it again” if tasked with the same choice, adding that it “is what it is.”

Don't be surprised if the 49ers star dons another shirt in the event of a 49ers-Cowboys playoff game.