*Space shuttle
Just kiddin'. A particularly inconvenient and embarrassing setting would, well, be any public setting; at the store, on a romantic date, at work, in school, etc. Or, perhaps a more private but intimate setting, such as with close friends or dinner with the family.
Family members might be shocked, but try and offer support during the change which, personally, would only make it all the more humiliating and embarrassing.
Being forced to change by a kinky lover would fall under the category of loss of control, which is extremely embarrassing to most people. The mate woule probably get a thrill from this.
Just my $0.02.
