The meaning of “三脚猫(sānjiǎomāo)” is equivalent to “jack of all trades and master of none” in English. At first, the word referred to a three-leg cat which was mistaken by people for a flying bear. Later, the word indicated the cats which were skillful in hunting but had difficulty in walking. Gradually, the word is changed to mean being unprofessional in doing things.
Nǐ zhèdiǎn sānjiǎomāo gōngfū xiǎng xiàhǔ shuí?
Your kung fu is so bad. Who do you think you can scare?
Bié kàn tā yí fù zhuānjiā de yàngzi, qíshí zhǐshì gè sānjiǎomāo bà le.
Don't be fooled by appearance. He is not an expert, but just a jack-of-all-trades.