What does j8傻逼 mean?
According to chinaSMACK, j8 is equivalent to 'penis' or any of its vulgar forms:

(rude language hidden behind spoiler, hover over or click to show)


   鸡巴
 jībā
 noun/adjective.

 Penis, dick, cock. When used as an adjective, it may mean “cocky”, “arrogant”, or a more generalized “fuck” or “damn”.