I think this is similar to "garage sale" or "yard sale", for used or secondhand goods
https://en.wikipedia.org/wiki/Garage_sale
Except the items are sold out of the trunk of a car

See this
https://www.thespruce.com/difference-between-secondhand-sale...
Boot Sale
The term boot sale originated in the United Kingdom, where the trunk of a car is called the boot. Sellers gather in a field, parking lot, or other predetermined location and sell their goods out of their boots.

Junk-in-the-Trunk Sale
A junk-in-the-trunk sale is the United States version of a boot sale, where merchandise is sold out of the sellers' vehicles. It's occasionally shortened just to trunk sale, but don't mistake it for the type of trunk sales offered by the fashion industry.

I would translate it like this
I'm actually having another one of my little trunk sales tonight.
سأنظم الليلة عرضا آخر في سيارتي لبيع الأشياء المستعملة

We don't need to literally translate trunk with صندوق السيارة

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Note added at 1 hr (2021-05-28 23:04:19 GMT)
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I just noticed that you said illegal or stolen goods might be involved. So no secondhand merchandise
سأنظم الليلة عرضا آخر للبيع في سيارتي

In the United Kingdom, they are known as "car boot sales" if the event takes place in a field or car park, as the vendors will sell goods from the 'boot' (called "trunk" in American English) of their car.

(Glosbe translate)
E

Example: "Its BACK ! Plymouth's Annual Old Village Yard and Trunk Sale event is April 24 2021 8AM-3pm ! As usual, start your "sale-ing" at the Trunk Sale at the Masons Lodge at 495 Amelia (at Farmer, next to the RR Tracks) . Anyone can sell there, just $20 for the first space and $15 each extra. Its a fund raiser for the Old Village Association. Shop several sellers there and grab a map and "Sale off" around Old Village to the Yard Sales at the homes of Old Village "

هو حدث تعرض من خلاله عينات محدودة في نقطة بيع أو في معرض للبيع

وفي بعض السياقات ممكن أن يكون المعنى
"بيع التصفية"



What’s the difference between a trunk show and a sample sale?

A sample sale is when we sell dresses that are already in store to brides at a deep discount. These dresses are called samples because they’re the ones brides try on in store before ordering a new version with their specific alterations and/or embellishments.
A trunk show isn’t technically a sale at all since the dresses are not marked as discounted. But most trunk shows do offer a discount for placing your order on the spot (sometimes up to 10 percent)
https://www.theweddinghq.co.uk/what-is-a-trunk-show/





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Note added at 1 hr (2021-05-28 23:16:49 GMT)
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trunk show
NOUN
North American
A sales event at which a particular designer or company presents their merchandise to potential customers, typically held in a clothes shop or the clothing department of a large store.
https://www.lexico.com/definition/trunk_show



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Note added at 14 hrs (2021-05-29 12:50:13 GMT)
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https://www.facebook.com/watch/?v=336517150515352
trunk sale!
We're holding our first annual Brothers Bar Trunk Sale Thursday, Dec 27! One night only! Many of our popular Brothers Tee Shirts throughout the year (extras, overages, etc) here for the taking!
هنا قد بمعنى بيع تصفية



https://www.facebook.com/watch/?v=845565672499225
Ivana's Trunk & Tag Sales
Last but not least... Come and shop the Estate Sale at 521 Simon Dr, Hartford tomorrow, Saturday, August 25, from 10-4pm.
وهنا تأتي بمعنى تصفية

Trunk-to-Trunk Sale
https://www.facebook.com/watch/live/?v=205246020595429&ref=w...
هنا بمعنى سوق شبيه بسوق الجمعة للتصفية لدينا

https://www.facebook.com/watch/live/?v=1552668344926293&ref=...
وهنا معناها بيع تصفية









Trunk sale:
من الناحية القواعدية هو اسم اصطلاحي مركب والاسم المركب له معنى مختلف عن معاني الكلمات الذي يتألف منها كل واحدة على حدا، لا تجوز الترجمة الحرفية هنا

It is a compound noun; the combination of the meanings of its parts together is different from the meaning of each word on its own.

Compound words are formed when two or more words are joined together to create a new word that has an entirely new meaning.
https://www.turtlediary.com/blogs/150-examples-of-compound-w...