Melón-melona, melocotón-melocotona

[ROBINDESBOIS]

Sometimes we use these two pieces of fruit to address sb, when I call sb melón or melona, I use it in a very affecting way, it means that sth is not going on well, but it is sth unimportant. It´s used in multiple contexts. For example if my brother buys the wrong food for my cat, I would say " que melón/melocotón estás echo" I repeat myself,it is a softener rather than a hardener, do you have a fruit expression or sth in English in both sides of the Atlantic.
Thank you.

[Ambarina]

Nunca lo había oído, Robin. ¿Es como decir "cabeza de chorlito"?

[poli]

No. In English there is no such comparison. Someone who makes silly
mistakes is a goof. This is a fairly new noun as far as I can tell, but
the verb to goof has been around for a long time. Example: I goofed
and bought the wrong cat food.
Or: Your silly goof, you bought the wrong cat food.

[bobjenkins]

quizás "melonhead"

[pjt33]

I think I may have heard "lemon" used in this kind of context ("You lemon!"), but I don't think it's very common.

[poli]

I think I may have heard "lemon" used in this kind of context ("You lemon!"), but I don't think it's very common.
I haven't heard lemon in this context, but I haven't heard of melon head either.

In the United States a lemon can be used to disrcribe an appliance that
is faulty. Most commonly it is used for automobiles that haven't functioned
well from the start.

[hermit]

"Melonhead" is the tightest comparison I can imagine...

[AngelicaDeAlquezar]

En México somos más amigables con las frutas... no usamos ninguna de esas expresiones. :D

[ROBINDESBOIS]

Nunca lo había oído, Robin. ¿Es como decir "cabeza de chorlito"?
kind of but softer

[Rusty]

cabeza de chorlito = scatterbrain

softer (varying towards more strong):

bonehead
blockhead
knucklehead
dummy
dunce
numbskull

[xchic]

I have heard lemon in the context of being sold a lemon. I can't say I've heard melonhead:thinking:

We often affectionately call someone a nana (as in banana) if they do something stupid.

[Ambarina]

I have heard lemon in the context of being sold a lemon. I can't say I've heard melonhead:thinking:

We often affectionately call someone a nana (as in banana) if they do something stupid.

Yes! I'd completely forgotten that one. :thumbsup:
That would definitely be the equivalent that RobindeBois is looking for but I have a suspicion that it's only BrE.