, also known as gookkake, gluekkake, ecto-porn, is a popular form of Japanese erotica

Pornography in Japan

Pornography in Japan.-Before the 20th century:Shunga or pornographic wood-block pictures were printed with all imaginable situations. These often took the form of a book with sentences to describe verbal utterances of the partners, as well as to offer brief descriptions of a scene...

 and prostitution

Prostitution in Japan

Prostitution in Japan has existed throughout the country's history.While the Anti-Prostitution Law of 1956 states that "No person may either do prostitution or become the customer of it," various loopholes, liberal interpretations of the law, and loose enforcement have allowed the sex industry to...

 involving the use of copious amounts of sex lubricant

Personal lubricant

Personal lubricants are specialized lubricants to reduce friction between body parts, or between body parts and other objects...

 which in the Japanese language

Japanese language

is a language spoken by over 130 million people in Japan and in Japanese emigrant communities. It is a member of the Japonic language family, which has a number of proposed relationships with other languages, none of which has gained wide acceptance among historical linguists .Japanese is an...

 is referred to as "lotion" (ローション). Typically it involves a participant rubbing lotion on another using their body, sexual intercourse

Sexual intercourse

Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

 in a pool or bath filled with lotion, or lotion being poured over the participants during sex. In Japan, lotion is available in concentrated form which can be added to hot water to produce the desired amount. The main component is polyacrylate

Sodium polyacrylate

Sodium polyacrylate, also known as waterlock, is a polymer with the chemical formula [-CH2-CH-]n widely used in consumer products. It has the ability to absorb as much as 200 to 300 times its mass in water. Acrylate polymers generally are considered to possess an anionic charge...

. A similar effect can be achieved by dissolving powdered methyl cellulose in water.