Bffr
Etymology
An initialism of "be for real," with a censored intensifier before "for real." It spread as internet and text shorthand around 2022, used both to challenge someone’s honesty and to react to something too ridiculous to take seriously.
interjection · /bee-eff-eff-AR/
A blunt demand that someone be sincere — or an exclamation of disbelief at something absurd.
What it names
It names the moment you refuse to entertain a claim or excuse — a compact call for someone to drop the act and speak or behave realistically.
Example
You’re going to run a marathon next week with no training? Bffr.
Related idea
Milder reactions like seriously? register surprise; bffr pushes further, demanding the other person stop pretending.