I've been bugging my wife to get a strapless dress since we moved to Hawaii, since the weather is awesome and I think she's a beautiful person. A month ago I brought it up again.
Me: You could totally rock a strapless flower print dress.
Her: I don't have a strapless bra and dresses are expensive.
Me: I can fix the bra part. How about we go to Ross? We could pick up a dress for like 10 bucks.
Her: What's Ross?
Whoa. What's Ross? Like, only the best store on the planet!
So I ordered a stick-on strapless bra on Amazon (being quite familiar with them, since I use them to make some awesome cleavage for myself). It arrives and I tell my wife "Now we have the bra, let's head to Ross." So we do, and she is in shock. Never been to one, didn't know they existed. We find two cute strapless dresses as well as some other stuff for the home. My wife is loving it. She gets to spend her Christmas gift from me (gift card to MAC) as well, so it might just be the best shopping experience in forever.
We get back home and head upstairs to have her try on the dress. She is hesitant. I eventually get her to agree to have me show her how to use the bra. Once it's on, with the dress, she can't stop staring at it in the mirror. Go me! At this point I figure I'm in the running for the "Best Husband Ever" award!
Later that night I figured out what the hesitation was. She had never tried a stick-on strapless bra before, and when she saw it in the package she connected it with my crossdressing (which, to be fair, is true). In her mind, the shopping and the bra was all about "me" and not about "her." I finally made that clear to her once I got her into the bra and dress, and then all was well.
So, for anyone still reading, if your wife is hesitant, remember that she might view your knowledge as an afront to her femininity (my wife's exact words were "I'm a little embarrassed you know more about bras then I do!") but if you work through it and make it all about her, it can work out great in the end.