explanation of “A surprise brother”

The joke itself doesn’t need any real explanation, but there are some notes about translation.  First, the Chinese version of the joke consistently refers to the older woman in the story as “the wife” (妻子) whereas in English, it feels awkward to write “the wife said to the daughter,” so we changed it to “mother” in most cases.  The phrase “小女儿的想法更酷” is a little funny too.  We can’t write “The daughter’s ideas were cooler.”  It doesn’t make sense.  This really means, “The daughter had an even better (cooler, more awesome) idea [than what the mother just suggested].”