meaning of "BS flag"

Howdy gangs;

Do you guys know the meaning of BS flag.
eg, I have to raise the BS flag on this post
or I’m tossing the BS flag my friend!

BS= BULLSHIT? AHA

Thank you for any input

It’s certainly not any sort of standard expression. But yes, you seem to have the meaning. You’re saying “This post is full of nonsense” when you raise the BS flag.