Fuzzy Lumkins is derived from the expression "there is an elephant in the room"- Fuzzy Lumkins refers to the metaphorical elephant in this saying. In other words, when there something obvious that stands out in any particular situation, like "an elephant in the room", the evident object is a Fuzzy Lumkins.
Where two people like each other and each individual is aware of the others feeling. However, neither party has explicitly acknowled the mutual fondness. In this senario, the love that they share is a "fuzzy lumpkins".