Phetchaburi is a nice little town about 3 hours by train south of Bangkok in Thailand. It's famous for a few things. Most notably Phra Nakhon Khiri palace, a style of egg custard and all the monkeys. There are lots and lots of monkeys. They're not everywhere but there are a few places in and around town that are crawling with them.
They are kind of adorable from a safe distance. Not so much up close. The ones in town have more or less lost their fear of humans. If you're carrying any food or drink or even carrying anything that could theoretically contain food or drink you're liable to have it confiscated by a snarling monkey. Someone we knew once had hungry monkeys set upon her and her shopping while she sat at a red light on her motorcycle. It adds a little excitement to otherwise mundane chores but doesn't make for a terribly relaxing time.
They're particularly to be found around the hill of Phra Nakhon Khiri. Most of the below video was filmed around there.
Here's that location on a map.
The advice we were given, that seemed to serve us well, was to avoid carrying food or drinks if possible in areas where you're likely to be around monkeys. If you must carry food or drink put it in a bag not usually used for that purpose. Avoid using plastic shopping bags in particular. The monkeys have long since figured out that plastic bags from supermarkets usually contain food.
Try not to stress too much though. Phetchaburi is lovely town and the monkeys are only to be found in isolated pockets. They can be aggressive little buggers but it is usually easy enough to avoid "monkey zones" or to avoid drawing their attention when you must be around them.