Just easier to remember when you need to map them to your internal virtual network or have to spoof them for whatever reason...
- 0xBADB00BFEED1
- 0xCAFEC0FFEE00
- 0xDEADBEEFFEED
- 0xDEFACEDBABE1
or make up your own: add, babe, bad, bed, beef, cafe, dead, deaf, decaf, deed, defaced, facade, face, fade, feed.