An example

When I see something I dislike, or some stupidity, I will call something "duck sauce". This saying is ironic.

My sister and I were skiing when we came up with this. There is an existing saying called "lame sauce", which is slightly ironic, because there is still the word "lame" in there, but there is obviously no "sauce" involved. "Lame sauce" is a saying, and "lame duck" is a saying, so I combined them to "duck sauce", a third saying carrying the meaning of the former.