I don’t recommend doing this, but I left an SD card in the breast pocket of a dress shirt and then put it into the wash. It went through warm water (but not the dryer; we don’t even have one of those, which is another story for an environmental blog).
After the Transcend 4 GB High-Capacity Secure Digital card went through the wash, I retrieved it and put it in my Mac. Lo and behold, it’s working fine. I remain amazed, and expect to buy more of these, but at higher storage capacities.