When your dad’s 2 liter of diet A&W pins down the throttle and simultaneously lodges behind the brake, causing rapid acceleration. This makes for a real bad time.
When you give a girl laxatives to cause her to have diarrhea, flip her over so her ass fills with shit (root beer), and cum on top of the pool of of shit (vanilla ice cream)
Person 1: How did your date go with Sarah?
Person 2: It went great, we saw a movie then I gave her the Root Beer Float in my car
upon finishing the activity of an "upper decker" (shitting in the upper tank of someones toilet) you then dump an entire bottle of dishwashing soap in the tank and then flush the tiolet so the bowl fills up with bubbling shit water....
Tom pulled an upper decker on Bills shitter, and I finished it off making it a root beer float!