The rain is causing a short and something should be thrown out. If this was a company and I saw electrical tape on an extension cord, I would report it to the safety person to have it disposed. - To repair it properly is usually just as expensive to just replace it. (electrical tape is not repairing it properly - I am an electical engineer and I work in Quality)

Despite what some cheap husbands want to claim, ext cords do not last forever and need to be replaced when damaged. This can be from general use, friction from cement removing the insulation, running it over or pulling it out of the wall improperly. Even though it may be heavy duty outside ext cord that does not mean it has a 100 year life.

Tell him to buy a nice outside extension cord - not a cheap one and your problems should go away. If not, give him a kiss, say your sorry, and return the new ext cord the next day. But that wont happen, you will have power of knowing you were right and your party will be great.

Oh and if its shorting out thats a good thing! That means no one will get a shock when they step in your puddles. Next time, dont do any rain dances until after halloween.