Bring Your Own Balls 

A phrase functioning as a bit of a warning that’s often used when you invite savvy investors into a high risk business venture that requires not only serious wealth but significant courage and stamina.

Only the uber-rich were even invited and the invitation itself included the acronym BYOB which in this case meant ‘Bring Your Own Balls’ since only the most intrepid risk takers would even consider diving into this shark-filled environment.

Bring Your Own Balls by Dr Bunnygirl June 20, 2023

Bring Your Own Fun 

It means BYOB but fun is substituted for booze. This is done because alcohol often starts the fun. The lone Sober person at a party does not usually have any fun.
Fun is also substituted as a code word so that minors don't have to worry about adults figuring out what is going to go on at a party.
The fact that it sounds nerdy and innocent makes it ironic.

Bring your own fun to the party saturday.
Should have brought some fun.

Bring Your Own Fun by Louis Richards January 2, 2008

bring your own bullets

used when you have crips up your arse and you want backup from your 2nd battalion

"hey guys wanna go barbecue? BYOB (bring your own bullets)" They then showed up fully armed to the teeth with guns and ammunition for the battle of their life.

bring your own bullets by nauseousthought October 31, 2023

Bring Your Own Sand 

The process of bringing your own sand to a beach themed party (in particular mall beach parties), and is almost always required as the hosts seldom provide any sand. It is often abbreviated BYOSand or BYOS on invitations.

Jackie Chan and Owen Wilson sent out Bring Your Own Sand invitations to their mall beach party.

Bring Your Own Sand by Anonymous09429852 November 25, 2010

bring your own guts 

Term coined by Clemson football coach Dabo Swinney to describe the mindset players should have for game-day. Clemson will give players on scholarship free tuition, but only the players themselves can bring toughness and determination to their game. BYOG means that players should play hard-nosed football with tenacity and spirit

Dabo: We give you stipends, and meals, and a place to live. We give you nice uniforms. I can’t give you guts. And I can’t give you heart. And tonight, hey, it was B.Y.O.G. Bring your own guts

bring your own guts by Hank28 November 28, 2023

Being your own ecosystem 

A term that members of the neohippie movement call not taking a bath for a long time. Some of them think it's more natural. But a lot of them just do it to piss people off.

John believes in being your own ecosystem.

Being your own ecosystem by Deep blue 2012 March 23, 2010