I guess as Poseidon or Neptune was considered Lord over any body of water (including the sea), probably the owner of that entertainment complex (the one Khun Tongrak refers to) considers Poseidon to be Lord over the water in a jacuzzi or a bathtub as well
Actually this kind of business should worship Cupid or Venus. Cupid has another name, Eros, which is the root of the word "erotic" in modern English.
The name of Venus, mother of Cupid, is the root of the word "venereal" in English. Long time ago we use to call KamaRok "veneral diseases (VD)" - the diseases of Love, or of Venus. Nowadays doctors call this kind of diseases STD - sexually- transmitted diseases.