An English equivalent of Arabic idiom ‘Show us the breadth of your shoulders’

Solution 1:

"Don't let the door hit you on the way out" is a well-known (though a dismissive, impolite) 'humorous' phrase.

I think it implies that the door is a "swing door" (or, a door being slammed on them on the way out).

Some people would tell you there's another (American-English) variant of this phrase, i.e. "Don't let the door hit ya where the good Lord split ya".

I don't recommend this variant:

• Invoking/involving the "the good Lord" in telling someone to begone seems to me uncharitable
• "where ... split ya" is a mocking euphemism for "bum crack" or "ass"

So this phrase is I think even more impolite than the one I suggested: Wiktionary describes it as a "nasty command to leave".

Unfortunately the type of "humour" even in the first phrase I suggested ("Don't let the door hit you on the way out") is a derisive humour: it is (in my opinion) mocking or belittling the person who you're dismissing. The phrase mentioned in the OP i.e. "show us the breadth of your shoulders" might (perhaps, I don't know arabic) allow the person to leave with dignity. If so then unfortunately I can't at the moment think of a corresponding English-language expression.

Solution 2:

There are a great many sayings, of various degrees of humor and various degrees of acceptance, which use the form, "Make like an A and B".

Make like a tree and leave.

Make like a shepherd and get the flock out of here.

Make like a banana and split.

etc.

This site http://www.rusbasan.com/Humor/Make_Like_A.html has more examples than you probably want to read at one sitting, although they are in the form, "Let's make like an A and B".

Solution 3:

"Close the door on the way out" is, I believe, a slightly less impolite phrase than the one ChrisW gave, although it lacks the anatomical connotations of the original.

"Close the window on the way out" is a bit cheekier ... implying the addressee should jump out the window.

Solution 4:

A couple more that are similar to get lost, but more humorous

Take a long walk off a short pier.

Or

Go fly a kite.

Or less humorous

Take a hike.