I don't know the exact meaning of the sentence "My cat washes its hair backwards", because it may be different after a long time. However, literally, this stalk may be a metaphor or humorous expression, indicating that someone is very unique or has some very unique skills or habits.

The description of "cats can wash their hair upside down" is very interesting in itself, because most cats can't stand upside down and are unlikely to show this behavior when washing their hair. Therefore, if this description is used as a metaphor or humorous expression, it may be describing someone who is very unique or interesting, or they have some very unique skills or habits.

In short, if you want to know the exact meaning, please confirm the context and context, or ask those who often use this stalk to get more accurate information.