Pittsburgh Steelers wide receiver George Pickens wrote an explicit message on his eye black for Sunday’s game against the Dallas Cowboys, and he reportedly could face discipline from the NFL.

According to ESPN’s Brooke Pryor, the NFL is reviewing Pickens’ “Open F–king Always” message for a possible fine under the league’s uniform policy.

Per Pryor, league rules state that players are prohibited from “wearing, displaying or otherwise conveying personal messages either in writing or illustration, unless such message has been approved in advance by the League office.”

Pryor also illustrated the league’s history of fining players for sharing personal messages on game day and Pittsburgh’s experience with those instances.

Steelers defensive lineman Cam Heyward was fined after a 2015 game for writing “Iron Head” on his eye black as a tribute to his late father. Steelers running back DeAngelo Williams was fined that same week for writing “Find the Cure” on his eye black in honor of his mothers and aunts whom he lost to breast cancer. Steelers defensive back William Gay was also fined that week for wearing purple cleats to support domestic violence awareness.

Pickens’ message was more of an individual shot toward his team. He has yet to reach the end zone this season and he has not looked like the No. 1 receiving option Pittsburgh expected him to be after his promising first two years in the league.

The 23-year-old played a career-low 34 snaps against the Cowboys, which ended in a 20-17 loss that dropped the Steelers’ record to 3-2. He was limited to three catches on seven targets for 26 yards and had some questioning his effort during his limited action on the field, so it doesn’t seem like the message on his eye black was accurate.

Steelers head coach Mike Tomlin said Tuesday that he was unaware of what Pickens wrote on his eye black.

“I don’t know what messaging you’re talking about regarding his eye black,” Tomlin said. “I didn’t have any outlying issue with his effort.”

Pickens will look to put forth a better showing when Pittsburgh visits the Las Vegas Raiders for a Week 6 clash on Sunday.