Salt. One of the main causes of water retention is eating too much salty food. The main component of salt is sodium, which the body dilutes with water if too much of it is present. Salt makes you thirsty, and your body will hold on to this water.
Or reject it, or counter-offer your terms. Usually you should hear back from the seller within 2 days, unless the seller is a bank (foreclosure) in which case they can take up to 10 days to get you a response.
I primarily do fixed price listings, and give the buyers 3 days to pay from the time they purchase the item or the time I accept their offer. You can open an unpaid item case after 2 days, and the buyer has 4 more days after that to pay - that will get you the eBay final value fees back. I'm not sure how it would work with a second chance offer, though. To be honest, a second chance offer at this point likely isn't worth it.