Depends on how many you have. I know people that keep em in buckets with small holes drilled into it and keep them in water next to their boats. You can also keep them alive in a cooler. I had about 3 dozen left over and "forgot" about them in my cooler. There was no ice or water in it and 95% were alive when I went back into it 3 days later. I think they're pretty hardy. If you are going to keep them out of water for more than two days I would recommend "flushing" them with some salt water so they can get rid of their wastes and keep their "lungs" wet.
I use a tall spackle bucket(7 gal.) with a lid and lots of small holes. I have kept half a bushel alive for more than two weeks without losing more than a dozen or so. I found they stay better if the bucket stays on the bottom.