Clunkers is a dog who appeared in the seventh season, in "The One Where Chandler Doesn't Like Dogs".
During Thanksgiving, Phoebe is secretly babysitting Clunkers, her friend's dog.
At this time, Phoebe is living with Monica and Chandler. They are upset, especially Chandler, who reveals to everyone he hates dogs.
The dog's gender is unknown. Monica referred to the dog as "she" while Chandler said he couldn't find "him".