The Vietnamese are deeply vested in the belief of the Lunar Calendar. Despite most activities these days go on with the Gregorian one, people still keep track of dates the old way. Many holidays and festivals are held on the occasions of the moon.
The current month is one that uses to recites fear in the heart of the living. In many Asian countries, Lunar July signals bad luck and curses of the wandering lost souls. It is believed that sometime during the first half of the month, the gate of hell is open and the ghosts from the Lower Realm will roam free on Earth. The ancestors and the deceased relatives will find their way back to visit living descendants. Other so-called "lost ghosts", which have no home and hear no prayers, will wander around, lost, lonely and bitter. The ancestors find their way back by tracing back the offerings and prayers of children, and upon feasting will bless them with good luck. Meanwhile lost ghosts, the ones with no relatives, forgotten by descendants or those who died without proper burial have nothing offered to them and will angrily curse bad luck upon strangers.
Vietnamese widely believe that July is the month that ghosts roam around and create trouble for just everyone. Many wholeheartedly blame their bad luck in July on the ghosts, and this contributes a major tank of gasoline added to the flame. To this modern day, even more than in the past, people often restrict from doing major projects or embarking on trips during this period of time. Others, mostly Buddhist practitioners, go on a vegetarian diet and pray for a rather unhealthy amount of time during the day. It is believed that the evil lost ghosts tend to stay with the likes of them, so the bad persons will end up paying a high price because of his companions. The atmosphere is more or less a "speak-easy", since bad luck is just around the corner and one cannot see it coming, or rather being thrown upon by the ghosts.
The most notable event of this month, July 15th is the Festival of the Hungry Ghosts. Vietnamese families will prepare two feasts during the day. The first one is offered early, usually at noon, to ancestors. The second one, often offered sometime after sunset, is meant for the lost souls. People sometimes go to temples to pray to deceased relatives, while monks ask Buddha to forgive condemned souls that have committed sins in their human days and are cursed to be hungry ghosts. Many people also bring offering to the temples and donate for the purpose of feeding these ghosts. After the monks finish their prayers, people are encouraged to act the part of the ghosts and fight for the food. It is a day that everyone eases up and forgives the sinful souls. For their sins, these poor ghosts are already cursed to never be full again - they are pictured to have long pencil-thin necks and huge bellies. (Not to mention that food in hell is probably not that good either!)
July 15th is the only day during the year that they can feast. Because they cannot eat proper food, the second offering of people usually consists of congee in very liquid form. Also, since Buddhism has that beings which do good and not harm living creatures will be rewarded, the offering to hungry ghosts are all vegan in nature. People trust that by restraining these ghosts from doing further evil - making them feast on no animal, they will be forgiven and one day regain their human form. It is a day of great compassion.
For many in Vietnam, it is common belief that living children should burn hell bank notes and joss paper to offer ancestors. These notes are believed to hold value in the afterlife, which is just a mirror image of this world. These days, the commodities include the latest techs and the most modern devices, from iphone to all types of vehicle and even entire houses. Upon the feast of the Festival, often at the end of the day, it is time for the fire to carry the goods to the other side. Depending on the regions, either at the end of July or right after the Festival, people will also light up lotus-shaped lanterns to guide the ghosts back in the afterlife. These lanterns are floated on rivers in great number, and when their light burns out, it is then that the ghosts have found their way back. These practices vary vastly by regions, for even the dates for the Festival differ greatly among countries.
Perhaps strange to most, the day of the Festival of the hungry ghosts also happens to be Vietnamese (Lunar) Mothers' Day. People pay homage to their parents and ancestors, be them living or deceased. The custom is that one spends some time to think of mother's great heart and be thankful. People whose moms have passed away will wear a white flower on their shirt during the day, while others whose moms are still will have a red one. This very simple custom is largely practiced throughout the country, and bears a very sacred and deeply unique mark of the Vietnamese culture.
As with every other cultures, there are always the ones who wish to bribe away their sins. Since Vietnamese believe that hell only opens its gate once a year, many think that they can pray and pretend to behave and get away with any evil for the rest of the year. These groups often flood temples with the most generous offerings, not only during the Festival, but year round. Unlike their miserable predecessors, monks these days are among the most well-off group of people. It has closed in being recognized as a full profession, and there is the new problem of fake monks praying on the pity and fear of the people. That says a lot about people these days!
On another side note, does it ever occur to anyone that with so many people burning hell bank notes, if there has ever been any concern for the inflation rate in the afterlife? After all, with so much money being sent down to the dead, there must be a rampant inflation problem going on.
For a less oriental-exotic and more western-friendly entertainment, National Geographic Asia is currently featuring a special, titled "Month of the Hungry Ghosts". The shows include new episodes of Is It Real and Mystery 360, which offer a more scientific look at supernatural phenomenon across the globe.
Have fun! And remember to stay safe during Lunar July!