I think a good "safe
" answer is to leer
and say "Take it off
, and I'll let you know
!" Add lip-licking
and slurping noise punctuation to taste
. This response has the double virtue
a) answering neither the question
nor the implication
b) inviting sex
It does not get you off the hook; it may be interpreted as a complete disregard for her appearance concerns. At least it has some potential positive results.
In one of the Philly Phrolics seminars I attended, the speaker noted that your lady is probably asking, NOT to put you in a double bind, NOT for a pat of reassurance, but rather because she simply wants to look her best. Think about it: if you were about to make a fashion blunder, you'd want to know, right? So, assuming she does in fact look fat in the dress, the tactful way to indicate it is by suggesting something that looks better. "I like the blue dress better than that horizontal striped one." "I think the red number is much more appealing."