If you plug it in while in Linux, use dmesg to see what device it gets assigned. Let's assume it is /dev/sda for this example. Now, run:
dd if=/dev/zero of=/dev/sda bs=4096
You may need to be root, depending on how you have setup the privileges for the device file. Make absolutely sure you put in the correct device file in the command above. It is very easy to wipe a filesystem this way.