Someone riding sideways on a motorcycle.
The birds in the tree are singing and eating worms.
The birds can't be riding a motorcycle while singing and eating worms.
exists e1 x1 x2.(on(e1,x2) & n_motorcycle(x2) & Actor(e1,x1) & v_sideway(e1) & n_riding(x1))
exists e2 e1 x1 x2 x3 x4 x5 x6.(n_tree(x5) & n_bird(x4) & n_tree(x2) & n_bird(x1) & Theme(e2,x6) & Actor(e2,x4) & v_eat(e2) & n_worm(x6) & in(x4,x5) & Theme(e1,x3) & Actor(e1,x1) & v_sing(e1) & n_worm(x3) & in(x1,x2))