On my first trip to Costa Rica I was on a hike with an american Guide in the reserve of Santa Helena in Monte Verde, we were a small group and there was this american couple who kept dragging behind, so they missed several useful tips when spotting capucin monkeys. Philip the guide told us never to point and laugh at capucins, because showing your teeth is a sign of anger. After a while we found ourselves surrounded by a group of capucin monkeys chasing some kinkajou. They got really aggitated and were making lots of noises, the american couple just looked up in amazement, started pointing and laughing, next thing you know the big alpha monkey jumps down on a lower branch, breaks off a good chunck of bromelia and throws it at them, which makes the couple laugh even more.
This makes the monkey even angrier and he just breaks off a branch the size of my leg and chuncks it at the couple, resulting in a bloody nose and a big bump on the husband's head.
This all happened in a matter of seconds, before the guide could do or say anything to the couple..... they kept close to the guide and were quiet the rest of the trip.

If some of you went to my flickr account, there are some pics of Costa Rica as well.

F.