pick coconut is an idiomatic expression of the Portuguese language normally included in the order "Vá catar coquinho!" and which means "go find something else to do" or "Leave me alone!". It is an expression used to drive away someone who is a nuisance.
There are several other similar expressions that have the same meaning as "pick coconut", and some of them are: "go take a shower", "go see if I'm on the corner", "go dry ice", "go inflate train tires", "go comb monkey".
In English there are several expressions that mean the same as "catar coquinho": "go take a long walk on a short pier" (the literal translation being: "go for a long walk on a short pier"), "get lost" (whose translation is "go get lost"), "take a hike" (go for a walk).
Popular expressions such as "go pick coconut" are very common because they suggest to a certain subject a activity often useless, simply so that the person using the expression can finally stay in peace.
Still about "pick coconut", some words emerged that complemented the expression, such as "go pick coconut on the slope" or "go pick coconut on the way down", which makes the act of "pick up" even more difficult coconut".