A feisty "Karen" went crazy on a group of skateboarders, got soaked by them and even got into a brutal fight with them ... all before cops showed up to detain her.

The truly bizarre scene went down Tuesday night in an Austin skate park, and the video starts with the woman -- who's barefoot for some reason -- getting aggressive with one of the skaters, saying ... "Who says I need help? It looks like you need help!"

Then she shoved a young skater, who kept trying to back away, before another dumped a jug of water on her. That's when an MMA fight broke out ... the woman started attacking with her bare feet, unloading kick after kick on young dudes and then a female skater jumped into the fray and kicked the crap outta the Karen!!!

Cops showing up didn't really calm things ... the Karen persisted -- they always do -- arguing with officers and busting out her phone to record the teens and accusing one of them of stealing her purse.

In the end, cops put her in handcuffs ... to the delight of everyone at the park. It's unclear if she was arrested. We've got a call in to law enforcement.