This is called zaghrouta. It is a way to express joy or happiness in Arab culture. Elements of it can also be found in other cultures even as far as music in the Balkans.
The English word for it is ululation. Wiki entry on it here: en.wikipedia.org/wiki/Ululation
There is also another theory that it is a Colombian custom which is also possible. Maybe it's a combination of the two?
More interesting stuff.
That's kind of neat.
Another perspective.
I am not a good judge of how good or bad it is. I just recognized it because I learned about it because I used to tune cars with some Lebanese friends and would hear it at stuff like parties and weddings then would notice it later in music and such.
More from someone that knows much more about the elements of that performance than I do.
I don't have a SoundCloud to plug but y'all can donate to this cool charity campaign.
Looks like @YahooSports deleted the original tweet I quoted. For those that are confused it was a clip of Shakira from the halftime show last night. 
