07:42 Oct 29 

Definitions of facer on the Web:

* (a dated Briticism) a serious difficulty with which one is suddenly faced
wordnetweb.princeton.edu/perl/webwn

* An unexpected and stunning blow or defeat
en.wiktionary.org/wiki/facer

And J.B. Priestley would never use the word "butt" in this sense except possibly if spoken by an American character, which Mr. Benenden is not - he is an English tobacconist living in London.

01:03 Oct 29 

as "in your face" "one back at you" "stick this in your gob and suck it" (literary of course), "Here's one back at you to rap your brain around"

00:58 Oct 29 

bum(mer) (butt) of a comeback that eh? Ie: not so cleaver

00:56 Oct 29 

"Smart ass comeback that eh?"