I went into buy a pair of jeans a few years back and the lady assistant asked "what waist size"? I said "ooh, well...I used to be a 32, but I suppose I've put on a bit since then, I'd say maybe a 34".
She smiled fixedly and said "let's just check, shall we?" God bless her for her professionalism. When I said "34" her face looked like this: