Philadelphia stand-up comedian Jamie Pappas was eager to get outside one Saturday morning and enjoy the nice weather. So the 29-year-old drove to the John Heinz National Wildlife Refuge in Tinicum to do some bird watching, writes Victor Fiorillo for Philadelphia Magazine.

She found, instead, a turtle slapping another turtle, so she recorded it on her phone, posted it to Twitter and it went viral.

As of Monday morning, the video had 3.4 million views, nearly 59,000 retweets, and more than 358,000 likes on Twitter.

“I put so much time and effort into my stand-up videos,” Pappas told Philly Mag on Monday morning. “But of course, it’s the turtles I post that get all the attention… Of course, slapping seems to be a thing these days. Very in style.”

Turns out it’s mating season for the turtles. The slapping is part of a courtship dance, says Heinz Wildlife Refuge biologist Garrett White.

“This video shows two Eastern Painted turtles in a courtship display,” White explains. “The male is the one doing the ‘slapping’.”

Turtle sex soon follows. Then nesting. Then lots of baby turtles.

The slapping denotes the male’s overall fitness, ability to maneuver in waters, and his nice claws. 

Read more at Philadelphia Magazine about this viral turtle video.