Commonly used in college kid houses where there is somewhat limited seating during large gatherings that arent quite considered parties. Person sitting in seat calls "SBV" and anyone else in the room says "dee-da-lee" in verification that when first person returns from wherever they went (to get food, use the bathroom, etc.) they will get their seat back.
In the case that someone steals the first person's seat, the first person can call upon the verifier (the dee-da-lee person) to prove that he had SBV.
This person verifies that the first person did indeed call SBV. If the seat-stealer is really concerned about sitting down, he can challenge the verifier to Rock Paper Scissors for the verifier's seat. (This is because the verifier agrees in verifying that he's willing to give up his own seat to let the first person keep theirs.)
It doesn't usually go this in-dept unless there is serious lacking of seating. Everyone usually loses interest after dee-da-lee is called.
Tim turns off the light and returns to find that Dave has taken his seat.
Tim: Scott? SBV?
Scott: yeah, i verified.
Dave gets up.
Alternately, Dave can challenge Scott with Rock Paper Scissors for his seat.