Lotion play has been popularized in Japan in an industry sometimes known as Soapland, where copious amounts of a a gooey lubricant is used for a full-body massage. "Lotion" here is not the moisturizing lotion in the traditional Western sense, but a methyl-cellulose or similar slimy, water-based substance.
The client is usually given a bath or a shower first, then the session is moved to an inflatable mattress where he or she is given a naked body-to-body massage, using the lotion. The client lies on his back and on his front, and the masseuse uses the lotion and her body and to slide over and massage the client.
The session may or may not hardcore sex, but almost always includes a hand-job and blowjob.