A boy on the soccer pitch wearing red shorts and a white shirt heads the ball, while being watched by two other players.
The boy showed off by heading the ball for his two friends.
A boy heading the ball does not imply he showed off.  Two other players are not assumed to be his two friends.
exists e1 e3 e2 s1 s2 x1 x2 x3 x4 x5 x6 x7 x8 x9 x10.(n_player(x10) & n_ball(x8) & n_pitch(x3) & of(x3,x4) & n_soccer(x4) & while(e2,e3) & Actor(e3,x9) & -(x9 = x10) & n_player(x9) & card_eq_2(x9) & Theme(e3,x1) & v_watch(e3) & Theme(e2,x8) & Actor(e2,x1) & v_head(e2) & subset_of(x7,x1) & n_shirt(x7) & a_white(s2) & Theme(s2,x7) & subset_of(x2,x1) & on(x2,x3) & Theme(e1,x6) & Actor(e1,x5) & v_wear(e1) & n_shorts(x6) & a_red(s1) & Theme(s1,x6) & (x3 = x5) & n_boy(x2))
exists e1 e2 s1 x1 x2 x3.(n_friend(x3) & card_eq_2(x3) & of(x3,x2) & n_male(x2) & n_ball(x2) & n_boy(x1) & by(e1,e2) & for(e2,x3) & Theme(e2,x2) & Actor(e2,x1) & v_head(e2) & a_off(s1) & Manner(e1,s1) & Actor(e1,x1) & v_show(e1))