The "/b/tards" strike again.

The teenaged pranksters of 4chan.org's /b/ discussion board flooded YouTube with pornographic clips Wednesday and Thursday, according to various reports.

YouTube has strong filters and dedicated employees seeking out and deleting porn from the site, but it wasn't enough to handle the onslaught of uploading clips.

To get around the filters, many of the clips appeared innocuous for the first 20-30 seconds, the tech blog Ars Technica reported, but then cut abruptly to hardcore sex scenes.

A spokesman for Google, which owns YouTube, said most of the porn had been removed by Wednesday afternoon.

"It may take some time for video search results and thumbnail images to disappear from the site," Scott Rubin told ArsTechnica. "Typically, this should not take more than a couple of days, but the videos themselves are no longer viewable."

Participants on 4chan's /b/ board and the similar eBaum's World site had declared Wednesday to be "Porn Day."

Previous 4chan pranks include flooding virtual-reality games with offensive characters and rigging Time magazine's "Time 100" poll so that its founder rose to the top.

The /b/ board also created the "Rickrolling" Rick Astley video craze, as well as the "LOLcats" fad of cat pictures with nonsensical captions.

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