Negative LIFO reserve?

I had previously posted about LIFO reserve and how to approach questions on the CFA exam, but I had a a great question about if it was possible to get negative LIFO reserve. While it is mathematically possible, I suggested that there might be some sort of accounting rule that prevents it (I thought it would look really awkward on financial statements).

When I asked my professor if it was possible, however, he was quick to point out that it was (both in theory and practice). When asked what real world scenario would this actually happen, he brought up the example of computer companies such as Dell and Cisco, whose technology products depreciate in cost (rapidly). It becomes apparent that they would:

1. Prefer FIFO accounting over LIFO
2. Probably have small, just-in-time (JIT) inventory management