What is bag-bagto?

BagBagto is a Filipino folk song.

The lyrics go like this...

Bagbagto, bagbagto-lambik,
Tulambik, tulambawikan,
Bawikan, bawikalanay,
Kalanay, kalanapunay,
Napunay, napunayagta,
Nayagta, nayagtagumba,
Tagumba, tagumbaya-aw,
Baya-aw, baya-atinbao,
Antinbao, Atin-bayanggaw,
Bayanggaw, bayang-gawistan,
Gawistan, gawistanabog,
Tanabog, tanabuga-ay,
Buga-ay, bugayesikan,
Yesikan, yesikamad-eng,
Kamad-eng, kamad-eyeng-as,
Eyeng-as, Eyeng-asaas...