Schools are closing for the summer and seniors are graduating, and that means teachers and principals everywhere can breathe a sigh of relief knowing they've survived another year of school pranks.

The best pranks are both hilarious and good-natured, like that of the pranksters who hired a mariachi band this year to follow their principal all day.

Other pranks are just the opposite, like the one committed by dozens of students charged with burglary and criminal mischief in May 2014 after vandalizing their high school overnight. (They didn't even prevent their school from opening as usual the next morning.)

But over the years, few pranks have been able to top this clever collaborative effort by more than 90 Minnesota high schoolers in 2006. Technically they didn't even do anything wrong, although plenty of motorists late for work might disagree.

Luckily, students caught this prank on video from multiple angles and uploaded it to YouTube, which we saw via Mental Floss.

At first, everything seems normal at the crosswalk in front of this Austin, Minnesota, high school.

On second thought, that's one large group of students. And why are they all walking single file?

Have patience ...

... or turn around.

Since the two school buildings the dozens of students are walking between are connected by an underground tunnel, the same kids can walk across the street over and over again.

They continue long enough for the line of cars to extend far down the road.

It's unclear how long they kept this up, although one student in the video states their intention to make it last 15 agonizing minutes.

Some of the students dressed up in cow and chicken costumes. We're guessing that may have been a clever way to drive motorists crazy when they saw the same costume make multiple passes.

Here's the full video: