HAhaha..

Always give the credit card company your mobile phone number.

I forwarded the story about the WW1 mines to my brother-in-law, a retired geologist here in Oz. He sent me the following information-

This tunnelling was carried out under the direction of Aussie geologists Edgeworth David & Loftus-Hills. David, through a combination of literature research on board the ship to Europe, and test boring using lightweight drills, had located a deep layer of impervious, compact clay in which the tunnels could be driven, although constant care was needed to avoid breaking out into the overlying, water-logged sands. The German army's geologists hadn't twigged to this clay horizon, and after the explosion were either returned to Berlin, or if under 40, sent to the front line.

Cash doesn't bounce. Or call your wife.