Hello! I will tell you how to change the MAC address of your network card. It may seem weird and unnecessary, but it could come in handy.

First you need to download a program called mac changer, here's how:

sudo apt-get install macchanger

After that, you use it like this:
sudo macchanger Option Device

Option here could be any number of things, including:
-h, --help Print this help
-V, --version Print version and exit
-s, --show Print the MAC address and exit
-e, --endding Don't change the vendor bytes
-a, --another Set random vendor MAC of the same kind
-A Set random vendor MAC of any kind
-r, --random Set fully random MAC
-l, --list[=keyword] Print known vendors
-m, --mac=XX:XX:XX:XX:XX:XX
--mac XX:XX:XX:XX:XX:XX Set the MAC XX:XX:XX:XX:XX:XX

I usually use the -r, --random option but it's up to you! As for the Device part, it's your network card. To find its name, go to System->Administration->Network Tools. Under Network Device, you'll find what you want. But generally speaking, ethernet connections usually have the name "eth0".

Example:
Say I want to change my MAC address of my ethernet card to a random new address. I do it like this:
sudo macchanger --random eth0


Hope you find this useful.