Pr0n is written leet slang for pornography.

This alternate spelling for "porn" is used regularly in legitimate communications (such as email discussion groups, usenet, and internet web pages) to circumvent language and content filters and to prevent search engines from picking them up. It has therefore become one of the only 'legitimate' forms of 1337 speak, (along with 1337 itself and warez), or leet speak that is commonly used. Not using pr0n could cause a huge influx of traffic, (enough to DoS some smaller sites or to bring an unwanted aspect to a web community), or cause accounts to be revoked even when they were being used for a legitimate discussion, or could cause e-mail to be marked as spam and ignored, et cetera.

"pr0n r0kc" is also the name of a rock music scene, geographically based in New Zealand. The scene has a satirical edge to it, but the music is honest. Leaders in this genre includes Greenpiece and Inverse Order. There is a somewhat official scene blog at a livejournal.