An impromptu toast among friends.
A group is at a party.
You can toast among friends anywhere, not just a party.
exists s1 x1 x2.(a_topic(x1) & among(x1,x2) & n_friend(x2) & n_toast(x1) & a_impromptu(s1) & Theme(s1,x1))
exists p1 x1.(exists x2.(at(x1,x2) & n_party(x2)) & n_group(x1))