Is this joke a positive phrase?

Yes The phrase with partial correction consists of two parts, the former part modifies or restricts the latter part, and the latter part is the core of the whole phrase. Generally, the former part is called modifier and the latter part is called head language. Attributive and adverbial are both modifiers. Modifiers in partial-speech phrases are called attributives, and modifiers in partial-speech phrases are called adverbials.