Here are five spa treatments for which you'll just need to let it all hang out.
1. Turkish Hammam: A Turkish Hammam is sort of a like a communal bath, where you spend time in rooms of varying heat. The highlight is having your skin nearly flayed off with a loofah. (Some people call the resulting ribbons of removed skin "spaghetti".) In a traditional hammam, this scrubbing is administered by a person wearing a bathing suit, and usually within few view of everyone else. My observation has been that people mostly avert their gaze from the scrubee, these are rarely attractive angles for anyone.
There are spas that offer a more modest variation on a hammam treatment. The spa at La Mamounia, for instance, has a shared steam room (which you enter wearing a bathrobe, leave it on or take it off as you wish), and then a private room for the scrub-a-dub, with private shower. The post-hammam moisturizer is applied in a communal relaxation room, so gaze aversion strategies are still a must if you don't want to get an eyeful.