What one feels when a person they wanted to date isn't interested or isn't worth the trouble. Shortened version of the term "other fish in the sea," meaning there's plenty other catches in this world, no need to waste time or hurt feelings over the one that got away.
The call that says it's time to direct your dating (or other) interests elsewhere.
She ain't giving up the draws, she's a f*ckin' golddiggin' *ss d*ck tease, let me stop wasting my time. Other fish.