Can two positives make a negative?

[bcdhgwp]

For homework, an English teacher in Russia asked the class to write a sentence about what they would do that evening. The next day, she asked each student to read their sentence.

One student said, "Last night, I took my girlfriend out to eat at a restaurant that was not inexpensive.

The teacher says, "That's a very good example of using two negatives to make a positive".

Another student asked, "In Russian, you can use two positives to make a negative, can you do that in English?"

The teacher thought for moment and said, "No, English doesn't have anything like that".

A student in the back looks up and says, "Yeah, right!"

The teacher thinks about what he said, turns red, and says, "OK, fine!"