A male-only auto-erotic sexual act wherein an individual laying on his back urinates in an arc, directly into his own mouth. Not to be confused with a Partial Rainbow, in which the individual need only hit anywhere within the facial region.
Ben: I was home watching Orange is The New Black last night when I got bored and did a perfect rainbow. Didn't spill a drop.
Jose: Damn man, you're sick in the head.
Jose: Damn man, you're sick in the head.
by Don's Johnson October 26, 2017