Shm-reduplication - Wikipedia
Shm-reduplication is a form of reduplication in which the original word or its first syllable (the base) is repeated with the copy (the reduplicant) beginning with shm- (sometimes schm-), pronounced /ʃm/. The construction is generally used to indicate irony, sarcasm, derision, skepticism, or lack of interest with respect to comments about the discussed object
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The construction originated in Yiddish and was subsequently transferred to English, especially urban northeastern American English, by Yiddish-speaking Jewish immigrations from Central and Eastern Europe. It is now known and used by many non-Jewish English speakers, particularly American English.
The most famous example of dismissive usage is the saying:
Cancer, shmancer, abi gezunt!
which mean something like "Cancer, who cares, as long as she's healthy!"