Essentially, flipping the hippo is a clean term that refers to sexual activities. The term is used as a verb phrase, and is often used to discretely discuss the weekend's activities without snoopers finding out your intentions.
(Friend to Friend, with others nearby) - We went out to dinner, and then that night we were flipping the hippo until she had to go back home.
The point at which a person with a FlipFlop addiction is forced to acknowledge that she has a problem. The FlipFlop addict will hide pairs of flip flops in various places around the house or in her car or flat-out lie about which ones are new, or how many pairs she has.
Helen hasn't reached FlipFlopRockBottom yet; she insists that having 83 pairs of flip flops is not out of the ordinary.