What does the joke "cucumber and eggplant" mean?

A newly married woman went to an adult store for the first time to buy condoms for her husband, but she never expected to know the size when she bought condoms. Because there are too many condom brands, she just picked a box of exquisite condoms and asked the shopkeeper, "Boss! Do you think this brand works? "

The proprietress was very excited when she saw it. She looked at her enviously for a few seconds and said, "Beauty! You are really blessed and have a good eye. Authentic Japanese 40' Okamoto' will make you extremely satisfied! " . . . . .

In the evening, the couple went to bed. After some caressing, the wife happily took out the condom she bought and proudly took out one and handed it to her husband. The husband took it in his hand and looked at it. Suddenly he was blindsided: "I said wife! What kind of condoms did you buy? I want an eggplant set meal, but you might as well buy me a cucumber set meal! No, the day lily is cold!