Reserve Price
  
You reluctantly agree to be a part of an auction, as in: you’re being auctioned off. Well, a date with you, anyway. For charity. You get to be nice and either get your ego brushed or...bashed.
You’d prefer the former to the latter, so...you tell the auctioneer you’ll only do it if someone in the audience agrees to bid at least $50 for you. You think a date with you is at least worth $50.
You could call that $50 your reserve price, the minimum price that the owner of the thing being auctioned will accept as the winning bid.
You could imagine how this would be important for auctioning off things, rather than dates. If you could sell a giant glass vase for $500 on the market, and it sold in an auction for $300, you’d feel like a Silly Willy for auctioning that vase. You can set a reserve price as insurance, in case it gets auctioned for...less than you'd like.