"Too stupid; didn't read." Used to warn new visitors to a site that one of the regular denizens habitually makes comments lacking in factual basis, logic, or perspective. Plays on "tl;dr," frequently used as a criticism of commenters who post walls of text to make points unworthy of the time either to write or read.
I see our usual font of idiocy has posted another ts;dr comment. If you value your brain cells you'll skip reading it.