An impromptu toast among friends.
A toast at a wedding.
There is no one specific place where you are limited to a toast, therefore they could have been anywhere, not just a wedding.
exists s1 x1 x2.(a_topic(x1) & among(x1,x2) & n_friend(x2) & n_toast(x1) & a_impromptu(s1) & Theme(s1,x1))
exists x1 x2.(a_topic(x1) & at(x1,x2) & n_wedding(x2) & n_toast(x1))