Using schm- to substitute for the first letter of the second word in a reduplication automatically makes the resultant phrase dismissive and contemptuous, neatly encapsulating, for example, my feelings about the lingering cold weather: Winter schminter!

Apparently this comes from Yiddish, where the word + sch- + [word minus first letter] concatenation performs exactly the same function.

Prescriptivists schmecriptivists!