People are riding in a crowded truck bed.
The people are talking to each other while sitting in the truck bed.
There isn't anything to indicate they are sitting - they could be standing in the truck bed.
exists e1 s1 x1 x2 x3.(in(e1,x2) & n_bed(x2) & of(x2,x3) & n_truck(x3) & a_crowded(s1) & Theme(s1,x2) & Actor(e1,x1) & v_ride(e1) & n_people(x1))
exists e1 e2 x1 x2 x3.(n_bed(x2) & of(x2,x3) & n_truck(x3) & n_people(x1) & while(e1,e2) & in(e2,x2) & Actor(e2,x1) & v_sit(e2) & all x4.(n_other(x4) -> to(e1,x4)) & Actor(e1,x1) & v_talk(e1))