What did he mean? "don't let those monkeys take your credit card!"

I am pretty sure that he was talking about actual monkeys.Watch out for the monkeys in the dark.

DAMN IT! Instead of reading "50's grey haired dude" I read "50 shades of grey haired dude"

Airports are notorious as places for pickpockets to ply their trade, especially in the Orient.
It is extremely common for the thief to slit your pocket or bag with a razor blade and remove your wallet, without you being any the wiser.
I don't see this as racial, but rather a derogatory term for these petty crooks, as monkeys will commonly steal anything they can get their hands on, and run away.

http://www.travelfish.org/orientation_detail/indonesia/bali/bali/bali_overview/168

Judging by the amount of theft that takes place in Bali, the cab driver was probably referring to the people in a racist way. That being said, it would be wise to watch your credit card, along with all your other belongings while on the island.

monkeys always steal things off people. some people train them to pickpocket etc. he could have meant the people though. either way it's good advice

Believe or not but there have been cases where monkeys have trained to steal items off tourists.

It wouldn't even cross my mind that he could be talking about anything other than actual monkeys. I have witnessed monkeys stealing from people, it's pretty funny.

Probably the actual animals

I don't think it's racist to call thieves monkeys. Monkeys are thieves.

You should've asked him for clarification. I don't think there are very many African people in Asia, so I doubt he was making a slur towards them. Assuming that he were also an Indonesian, while it is possible to be a self-racist, it wouldn't make sense for him to group his people, himself included, into a racial stereotype. Then again, since when has racism ever made any sense?

I'm thinking that he may have meant both thieving primates and people.