Austin Adams is still quite angry at the Mets for designating him for assignment.

After he mocked Jose Iglesias and the team’s “OMG” celebration Tuesday after escaping a fifth-inning jam, the A’s reliever unleashed an expletive-filled barrage at his former team.

The Mets signed Adams in the offseason before designating him for assignment in February and then shipping him to Oakland in March.

Warning: Graphic language

“F–k out of here, you piece of s–t,” Adams appears to say, according to Jomboy — baseball’s lip-reading expert — after striking out Francisco Alvarez to escape a high-pressure jam in Oakland’s 9-4 win.

“You guys are f–king s–t. You f–king DFA me? Shut the f–k up.”

Adams never appeared in a game for the Mets but it’s clear he’s holding a grudge for how the team treated him after signing him to a one-year non-guaranteed deal in November.

The Mets designated him for assignment after signing Jake Diekman right before spring training started. He remained in camp, posting a 5.68 ERA spanning seven games.

The Athletics then acquired him for cash considerations in a March 24 trade.

Tuesday marked his first game against the Mets and he made his former team pay by escaping a two-on, no-out jam in a 7-4 game, punctuated by the strikeout of Alvarez.

After Alvarez whiffed, Adams looked at the sky and extended both arms outward and then to his mouth and then out again to mimic the dance to Iglesias’ hit song and the Mets’ home run celebration.

Adams then turned toward his dugout and walked off the field while hurling the expletives.

He claimed there was no ill intention behind his “OMG” celebration and it had not been planned.

“Honestly, I looked up and was so surprised I got out of it. I was like, ‘Oh my gosh.’ And then it dawned on me, I was like, ‘Oh my gosh,’” Adams said. “So, then I did it. I mean, that song is sick. Iglesias is a good dude. So, hopefully no one is offended. Just having fun.” 

Adams noted that the Mets moving on from him fueled him.

He has been a reliable piece for the A’s this season, posting a 3.92 ERA spanning 56 games.

“I got DFA’d three days before games started over there. I mean, I’m a middle reliever, so I mean, that just happens with the job that I have,” Adams said. “I got out of a huge jam that helped the team. 

“I pitch on emotion. I maybe need to do a better job of not doing that. But, at the end of the day, big-time situation in a game. Got some big outs, got the team a win. You know when you get DFA’d you’re told you’re not good enough to play for a team anymore. You know it sucks, so yeah had a little extra juice today.” 

Mets closer Edwin Diaz told The Post he did not appreciate Adams’ actions.

“He crossed a line because that’s something we do when we hit a homer or something,” Diaz said.

“He (can) do it always, that’s fine. But, he can’t get mad if we do something to him the next couple of days.”

The Mets and Athletics meet for the second game of the three-game set Wednesday.