An impromptu toast among friends.
Friends are having a drink.
Having a drink is rephrasing of impromptu toast.
exists s1 x1 x2.(a_topic(x1) & among(x1,x2) & n_friend(x2) & n_toast(x1) & a_impromptu(s1) & Theme(s1,x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_have(e1) & n_drink(x2) & n_friend(x1))