I usually buy anything

(Grammar Questions I Couldn't Answer)

A reoccurring point of confusion in the ESL classroom is the difference between "every" and "any".  For example, when offered a choice of foods in a restaurant role play (e.g. "What food would you like?") a student will often respond, "Everything is okay."

I've been taking a lot of pains lately to correct this.  "No, if you say 'everything is okay', it means EVERYTHING.  You want to eat ALL the food.  If you only want one, but you don't care which one, you can say, 'Anything is okay'."

But the other day, we were talking about online shopping.  The question was, "What things do you buy online?"
"I usually buy anything online," a student answered.

It sounded wrong to my ear.  In fact, I think "I usually buy everything online," would have sounded better, even though this goes against what I had been teaching my students for months about the difference between "every" and "any" .