An engagement ring with a large and flashy diamond; perceived to be expensive (and often is).
When worn by a girlfriend/fiancee the message communicated by the ring is "BTFO, I paid for this. She's mine... and she knows it."
Sometimes perceived as frivolous spending, the BTFO Ring may instead be a sign of:
(b) distrust, or
(c) high-maintenance women.
"Hottie at the bar... I'm moving in."
"Good luck -- Check out that BTFO Ring... You don't stand a chance."