Problem with :action => 'destroy' in url_for

url_for( :controller => ‘foo’, :action => ‘destroy’, :id => 1 ) => ‘/
foo/1’
url_for( :controller => ‘foo’, :action => ‘destroy_x’, :id => 1 ) => '/
foo/destroy_x/1
url_for( :controller => ‘foo’, :action => ‘destroy’, :foo_id => 1 ) =>
‘/foo/destroy/?foo_id=1’

Anybody knows what happens? No REST routes defined.