The term "pattern-bomb" is not a commonly used word in English, but we can break it down to understand its meaning better.
Pattern-bomb (verb): To "bomb" something usually means to fail spectacularly. When combined with "pattern," it refers to the action of failing in a repeated or systematic way.
In more advanced contexts, "pattern-bombing" can be applied to various fields, such as sports, academics, or creative endeavors, to indicate a systematic failure in performance.
While "pattern-bomb" itself is not an idiom, you could relate it to the idiom "fall flat," which means to fail completely: - Example: "His presentation fell flat, much like his previous attempts."