meaning of "BS flag"

[Davy07]

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

[Barb_D]

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.