You're lucky it did not happen in Cebu. Cebu -The Japanese citizen Kazuaki Sato was arrested late on Friday afternoon, after he wanted to pay with a fake 1,000 PHP bill in a pharmacy along F. Ramos Street, Cebu City. The head of the pharmacy Sharon Narra had, the Investigation and Detective Management Branch (IDMB) of the Cebu City Police Office (CCPO) informed, when he realized bill validator on its UV light, that it was a fake 1,000 Peso banknote. The alleged false 1000 PHP bill was passed the Central Bank for review, Sato is now in the Tourist Action Center, detained outside the Cebu City Hall. EPD 09/05/2015 - 4:25
So if you happen to be given a fake bill by someone and unknowingly spend it you get arrested (and probably deported). Brilliant.