J.J. Watt mocks Zach Mettenberger with selfie celebration after sack

Zach Mettenberger seems to love posting photos of himself on the Internet.

But J.J. Watt provided a shot that the Tennessee Titans quarterback probably won't be sharing on social media anytime soon.

Making his first NFL start on Sunday, Mettenberger was tormented by Watt on the field, as the star defensive end sacked the rooke twice, batted down a pass and forced a fumble to lead the Houston Texans to a 30-16 victory.

After the second sack, Watt stood over Mettenberger and posed as if he was taking a selfie. Watt later said it was meant to send a message to the young quarterback.

"It's just kind of a reminder, this is the National Football League, not high school," Watt said. "Welcome to the show."

Mettenberger apparently stopped cutting his hair and shaving his beard at the start of training camp. When he was named starter last Thursday, the sixth-round pick out of LSU decided to do some grooming. But only some -- he ended up giving his first interview as the Titans' starting QB with shaggy hair (contained by a red headband) and moustache.

"The plan was always to clean myself up when I was named starter," he said. "That came a little sooner than I anticipated. With media coming, I wasn't able to get a haircut, so I thought I'd have fun with it.

The fun spilled over to social media, as Mettenberger posted a couple of photos of his quickly evolving look on Instagram late last week.

#StashSelfie

A photo posted by Zach Mettenberger (@zachmett7) on Oct 10, 2014 at 5:53am PDT

New look is ready to go

A photo posted by Zach Mettenberger (@zachmett7) on Oct 10, 2014 at 1:17pm PDT

"Ultimately that's what this game is about -- it's about having fun," said Mettenberger, who threw for 299 yards with two touchdowns on Sunday. "Anytime you get an opportunity to show some character or personality, you've got to make the most of that."

Mettenberger seems to have thought one of those opportunities arose just about 90 minutes before gametime, when he decided to tweet out one last selfie.

That might have been what pushed Watt over the edge.

"I just, I take my job very seriously," Watt said. "If I was a rookie quarterback being named the starter for the first time in the league, I feel like I'd be a little bit more focused than that.

"Maybe he'll learn from it, maybe not. We won the game, so that's all that matters."

Twitter: @chewkiii