but tell me, which chinese comedian didn't do that?

ever since the fashion with cell phone and net, duanzi are all over us. according to my limited law knowledge, there's no copyright and every1 can use them. it's like those old revolutionary songs, many were using chinese folk song soundtracks, as long as new writers ackknowledge that fact, i think it's fine. organizing previous works, though not original, still is soemthing one should give some credit.

has zhou or guo clearly claimed their lines were all original?

my admiration for zhou is mainly he survived by himself and friends, wiht no backup from government