Magical Unicorn Mask
The horsehead mask is great in every way, we're not complaining about it. It's awesome, and yet it's just a simple horse.
The unicorn on the other hand is a rare and magical creature with powers that defy description. And while the unicorn mask is a creation of man, it is still imbued with a fraction of the magic power of the real unicorn.
For instance, gives its wearer the ability to be the life of every party. Members of the opposite sex (or same same if the wearer prefers) are inexplicably attarted to the wearer. Money flows to the wearer as does free drinks. The old quote "Women love him and men want to be him" applies in the situation (reverse for women).
In short, just about anything you want to accomplish can happen with the aid of a magical unicorn mask. You've just got to believe...
And even if you don't believe in magic, well, it's still a pretty fun and funny looking mask! It can still make people smile, and that's a special sort of magic in itself, dontcha think!?