The saying goes, "Don't feed your wife autumn eggplant". Three potential reasons are given for this adage: 1) It could have an unwanted cooling effect on her body. 2) Its minimal number of seeds could curse her with reduced fertility. 3) Since the "wife" kanji can also mean "daughter-in-law", it would mean wasting some very tasty food on someone the mother-in-law doesn't feel deserves it.

The opposite of this would be...

"Don't feed your husband a lunch costing over ¥300"!!

...would be "Don't feed your husband a lunch costing over ¥300", but...

...what are ya supposed to make if there ain't nothin' in the fridge but eggplant?