Okay... well not the way you all want me to define it.
(You're all hating me now, but I swear I will spill my guts soon. This hippo is too big to keep under wraps.)
The metaphor I am borrowing came from this book series. If you haven't read them, GO READ THEM. Some super romantic, serious vampire loving - and an adorable vamp heroine who loves Prada and Manolos. Lots and lots of love in them.
I think Eric Sinclair talked about his hippopotamus of joy in this one (book 5):
I love a good hippopotamus.