Jerkfish is a fabled aquatic creature that eats lures but has never been caught
Jerkfish must be living in this lake; I wasted all my lures but caught nothing.
Someone who is acting like a jerk–– used in more playful terms than to truly insult the jerk-like character.
Can also be used for other adjectives: (DORKfish, LAMEfish, MEANfish, etc.)
JoeBobSmith was poking fun at my pwned state, so I said he was a jerkfish.