I've always kept my dressing hidden. I got a cheap Halloween wig and decided to go through drive-thru in the wee hours. My voice cracked but I think that with the mass of brassy blonde hair I was good until I got to the payment/pickup window. The lady took my money, asked if I wanted a little or a lot of ice (I cracked back "a little") then brought my drink. As she started to wish me a good day she hesitated slightly, ending with have a good day, baby.
So I think that I did pass for a minute but my voice gave me away finally. Still, she was friendly and I bought something en femme!