Here’s how it works (in case you didn’t know). Find a calculator—a single line LCD display one, not a fancy thousand-button monster or the Windows calculator (!). Turn the calculator upside down. When you punch in the numbers, they will look like crappy LCD versions of letters. The challenge is to spell words using those letters; 3045, for example, will read “ShOE” when it’s upside down.
Yeah, it’s lame, and yeah, it’s old school. But back in the days before the Internet, we’d amuse ourselves by typing in such choice numbers as 7734 or 5318008 and snickering over the results.
Ah, good times.
And just for fun, here’s some links related to calculator spelling: