It’s not the mind-numbing repetition or lack of any real payoff after success that makes plastic water bottle flipping annoying to adults. It’s the sound.

Listening to liquid slosh back and forth, followed by a thump and the crunch of cheap plastic giving way to the laws of physics — over and over and over again — is what’s driving parents of students and their teachers crazy.

Bottle flipping went viral last May after a high school student in North Carolina took part in a talent show and was filmed while dramatically performing the stunt; the video has been viewed more than 7 million times since it was uploaded to YouTube. It really went mainstream on Dec. 7 when NBA superstar LeBron James was caught on camera flipping a bottle with teammates while on the sidelines of a basketball game still being played.

“When you’re walking through the halls and (students) flip them over your head, I’m like, ‘Really?’ It’s during recess time, lunch and before school,” said Dole Middle School teacher Aimee Clanin. “The crinkle sound the bottles make are like nails on a chalkboard. But as a STEM (science, technology, engineering and math) teacher, it’s actually a science lesson in itself. So the general consensus is (that it’s annoying), but they could be doing worse things, right?”

Those in the know consider it a success when one grabs a water bottle by its neck and tosses it in the air so that the bottle completes a single end-over-end flip and lands upright without falling over.

“It’s unpredictable, so it’s hard to tell if you’re going to get it to land or not,” explained Kaimuki Middle School sixth-grader Vincent Grillo. “But once you have a knack for it, it’s a lot easier to do and you can challenge your friends. It feels satisfying when you make it flip.”

Grillo, 11, said security staff had banned the game on campus, but a spokesperson for the state Department of Education confirmed bottle flipping has yet to be officially outlawed from public schools on Oahu.

“Kids could be doing it outside of school hours, but I can tell you … there hasn’t been any concern expressed,” said DOE director of communications Donalyn Dela Cruz. “It hasn’t drawn attention by our school administrators at that level just yet.”

Dela Cruz said the last time letters were sent home to parents banning something was when Japanese kendama toys were popular a few years ago and students were playing for keeps (i.e., gambling). Other than a comeback of pogs and the recent rise of the “Mannequin Challenge” (in which kids video a group of people holding still as if life has been put on pause), things have been pretty quiet this year, she said.

Grillo’s father, local photographer Tony Grillo, said as a former bartender it’s pretty neat to see his son picking up a hobby he’s always enjoyed. “I do that a lot naturally, so I didn’t really notice him doing it at first,” he said. “I just flip and catch them in one hand, but he actually tries to land it.

“I don’t see anything bad about it. It’s all about improving hand-eye coordination for me, so I like to see him doing stuff like that.”