B.Y.O. or B.Y.O.B. traditionally suggests Bring (you own....) and the optional, final "B" could refer to Booze, Beer, or a Bottle.
And "Bottle" could mean a container of strong liquor, which is also known as Dutch Courage (or Irish Courage), or in some parts of the word "bottle" is slang for courage itself.
Metonymy is a particularly useful literary device for alien romance world building, if one would like one's aliens to have their own slang.
This is an excellent starting point:
B.Y.O.B. could also stand for BUY your own BOOK. Apparently, it is an established practice, especially among politicians.... and among writers with bread to cast on the waters.
Sarah Nicholas of Book Riot has an interesting History of Buying Books onto the Bestseller list, from how it all started up to the present day and what those little dagger signs signify on the N.Y.T. bestseller lists.
The article may not be quite even handed. One can be fairly confident that the counterparts of the cheating authors who were cited probably did the same thing, and may even have used taxpayer funds instead of mere campaign donations.
One might also find that Amazon will delete bad reviews for very well connected friends of Amazon, but for most authors, even bad reviews of books that have not been published, let alone sold, will stay up in all their miserable glory.
Amazon is also in the writing world news for (another) instance of rather poor quality control. "Waffle" is hardly literature, but one follows ones stream of consciousness, if only for the joy of the pun!
A Canadian over Christmas showed a little too much bottle (as in "willingness to take risks") when he took to social media to lambaste his American corporate employer over their seasonal gift to him of barbecue sauce. We are not told if it is the type of sauce that comes in a bottle.
His sauciness was not appreciated, and he lost his employment.
The American First Amendment protects one's right to speak one's mind, but does not guarantee freedom from the consequences of ill-advised speech... as CNN also discovered, and as is an object lesson to any humble participant in social media discussions of current events.
While DuckDuckGo-ing "B.Y.O.B.", one notices many references to a music group by that name. This blog is not about them, but they may deserve attribution for turning the acronym to "Bring Your Own Bomb".
But, on the topic of bombs, Colin R. Jennings, Ann J. LaFrance, Garon Anthony and Ericka Johnson blogging for the law firms Squire Patton Boggs, give timely advice for all internet users on preparing for the possibility of a well-coordinated cyber attack.
While an international cyber offensive would not be directed at alien romance writers, it might sweep us up in collateral damage if we could not back up our files to our preferred cloud, use credit cards, access our banks, etc.
All the best,