Personally I think of
'The Mexican Hat Dance' tune when I think Mexican. I reckon between Mr Hahn and Mike alone they could knock up a pretty listenable rendition of it
*as Chas dances around a big sombrero on the ground*
*as Rob has a siesta in the shade of a hascienda*
*as Brad picks the cactus needles from his untamed afro*
*as Phoenix... *** only knows*