Some people seem incapable of comprehending sarcasm. In fact, damage to certain parts of the brain does hinder one's ability to comprehend sarcasm.
The left-hand side of the brain processes literal meaning. The frontal lobes and right- hand side of the brain process the social and emotional context. The most important region to comprehending sarcasm, however, is an area called the right ventromedial prefrontal cortex.
It's located behind the forehead. It takes the information from those other areas and puts it together. If the context of what's said puts a spin on the literal meaning of the words, this is the part of the brain that figures that out. Damage to any of these involved areas may hinder one's ability to detect sarcasm, but in studies, people with damage to the ventromedial area demonstrated the most difficulty in comprehending sarcasm.