Maybe don't wear this dress out for dinner with your in-laws. But I could imagine some situations where the Intimacy dress by designer Daan Roosegaarde could be useful. In a nutshell, the dress contains "e-foils," which are opaque coils made of "electronics, LEDs, copper and other media." In response to your heartbeat, the coils become "more or less transparent," and this is supposed to reflect "close and personal encounters with people." So the dress becomes more see-thru if you're turned on or happy — but probably also if you're pissed off. Like I said, don't wear it to dinner with the in-laws.
Intimacy has been around in prototype form for a couple years, but now it's actually coming on the market in time for Valentine's Day. Here are a couple pics, showing Intimacy Black and Intimacy White: