Allen said the following in the comments section of an Instagram post from a fan account of Broncos cornerback Chris Harris: "Now, y'all know damn well that boy can't hold my jockstrap. Stop it."
Allen confirmed those comments to reporters in the locker room Thursday.
"Go watch the tape, man," Allen told reporters. "It's not a secret."
Allen finished with a season-low four catches for 18 yards on six targets in the 20-13 loss to the Broncos last week. The Chargers (2-3) failed to score a touchdown on offense for the first time this season.
"I guess it was a tough day ... for the offense," Allen said when asked about the team's struggles. "... Turnovers in the red zone a couple times, couldn't get it done. It was turnovers. It was self-inflicting wounds."
It's not the first time Allen has criticized Harris and the Broncos. He also did it last season after the Chargers' 23-22 loss to Denver.
"No, I don't think they played well at all," Allen said after the 2018 loss. "We dominated the game. Turnovers. We gave them some points and that's what happened. They suck."
Allen leads the Chargers in receptions (38) and receiving yards (470) through five games. He also has three touchdown receptions.