Spain's national anthem has no words, but a proposal just made in Congress would create a commission to propose official verses.

The song is the "Royal March," which you can hear (where else?) at Wikipedia:
http://en.wikipedia.org/wiki/Marcha_Real

Over the years, it has had various unofficial words, and during the Franco dictatorship, the very unofficial ones -- still dear to the hearts of many Spaniards -- were:

Franco, Franco, que tiene el culo blanco porque su mujer, lo lava con Ariel.
Franco, Franco, has a white butt because his wife washes it with Ariel [a laundry detergent].

It will be hard to beat that.