I think it’s just about an old folk dance (?) called La Bamba (La Pumble). I taught myself to sing it after watching the film about Ritchie Valens, called La Bamba, surprisingly .I bloody love that song even though I have no friggin idea what it’s about. Pumble now, I guess!
One of my favourite lines is:
Yo no soy marinero
Soy capitán, soy capitán, soy capitán
which means - I am not a sailor, I’m the captain
(Or in Jack’s case, I’m not a fireman,
I’m the chief, I’m the chief)