Melón-melona, melocotón-melocotona

Melón-melona, melocotón-melocotona
 

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.

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

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.

quizás "melonhead"

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.

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

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

kind of but softer

cabeza de chorlito = scatterbrain

softer (varying towards more strong):

bonehead
blockhead
knucklehead
dummy
dunce
numbskull

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.