Fellows writing on the back of a friend with black markers.
People are writing silly things on their friend's back with markers.
It does not say in the context above if they are writing silly things on their friends back.
exists e1 s1 x1 x2 x3 x4 x5.(n_back(x3) & a_topic(x1) & on(e1,x3) & of(x3,x4) & with(x4,x5) & n_marker(x5) & a_black(s1) & Theme(s1,x5) & n_friend(x4) & Actor(e1,x2) & v_write(e1) & (x1 = x2) & n_fellow(x1))
exists e1 s1 x1 x2 x3 x4 x5.(Theme(e1,x2) & Actor(e1,x1) & v_write(e1) & on(x2,x4) & with(x4,x5) & n_marker(x5) & n_back(x4) & of(x4,x3) & n_friend(x3) & of(x3,x1) & n_thing(x1) & n_thing(x2) & a_silly(s1) & Theme(s1,x2) & n_people(x1))