Dogs may be man's best friend, but only when we're telling them the truth.
According to new research, our canine pals can tell when a person is lying to them.
The study, published in the journal Animal Cognition, suggests dogs are capable of learning which humans they can rely on and which they can't.
A total of 34 dogs were tested by the researchers from Kyoto University, Japan.
During the first round of tests the dogs were pointed in the direction of a bowl filled with scrumptious dog food.
Then in a second round, the dogs were shown to a bowl which was empty.
In a final third round, the dogs were pointed to the bowl again, this time with food inside. However, the suspicious pups did not respond.
Akiko Takaoka, who led the study, told the BBC she was surprised that the dogs "devalued the reliability of a human" so quickly.
"Dogs have more sophisticated social intelligence than we thought. This social intelligence evolved selectively in their long life history with humans," she added.
This isn't the first study to suggest that dogs are extremely good at reading human behaviour.
Research published in the journal Current Biology earlier this month suggested dogs can recognise emotional expressions in another species - including humans.
"Our study demonstrates that dogs can distinguish angry and happy expressions in humans, they can tell that these two expressions have different meanings, and they can do this not only for people they know well, but even for faces they have never seen before," study co-author Dr. Ludwig Huber said at the time.
So next time you're teasing your dog (in good nature of course), know that he's probably already got you sussed.