Do not do this at Yellowstone, ever.
One of North America's great natural wonders is Yellowstone National Park. This sprawling area has the perfect combination of geologic wonders and wildlife. Often, you can see both in the same area while walking the park's many boardwalks to see beautiful hot springs and geysers.
One commonly encountered animal is the bison. They are practically everywhere in the park and are almost guaranteed to be the first animal you will see during a visit. They may look slow and dim-witted, but these are not animals to mess around with.
Just to drive that point home further, we present exhibit A of improper tourist behavior when encountering a wild animal in Yellowstone. There is a rather large bison standing just off a boardwalk. Some of the tourists are trying to get by, others are wanting to take photographs. In either case, they are all way too close to a wild animal. The bison gives off plenty of warning signs before finally making a charge at the humans.
We simply have no words for this one. We have seen some examples of dumb behavior in the park before, but this one takes the cake. That bison was giving multiple warning signs to the group to back off and they kept on approaching it anyway. The group ignored the countless warning signs and the warnings of the rangers when they entered the park to not approach wild animals. In fact, the park advises staying at least 25 yards away from large herbivores and at least 100 yards away from large predators.
One thing we cannot get over is the guy in the blue shirt who is laughing the whole time. This is not a Disney theme park or petting zoo with tame animals. The child the bison chased around that downed tree could have easily been trampled and killed, and he is still laughing after the fact. Scary stuff.
So, if you are heading into Yellowstone this summer for your vacation, keep your distance from the bison. This incident ended with no one hurt, but plenty of people have been trampled in the past. Bison are cranky, give them some space!