Stupid is as Stupid Dogs

It is official. I have the dumbest dog in the world. Bo just randomly started barking like a complete maniac. What was he barking at?
























My wall calendar that has had the same picture on it since July 1st (naturally). And just in case you don't think he was pissed that it was a picture of a dog, he became more agitated when we praised and petted the picture.

Updated to add:

Perhaps this is a manifestation of intelligence on Bo's part. This article suggests that dogs are actually able to interpret the contents of photographs like humans do. Bo is really a savant.