Avocados and milk

A wife asks her husband, "Could you please go shopping for me and buy one carton of milk and if they have avocados, get 6”.

A short time later the husband comes back with 6 cartons of milk. The wife asks him, "Why did you buy 6 cartons of milk?"

He replied, "They had avocados."

Note:
If you're a woman, I'm sure you're going back to read it again!
Men will get it the first time. My work is done here.