I went on YouTube to see if I could find some cicadas to compare with, since they're the only zappy-sounding insect I could think of. I played some clips, and they didn't sound exactly like the thing outside. They did sound like electrical zaps though, so I felt confident that the thing outside could in fact be an insect, and I decided I could more or less put the issue to rest.
I clicked on a couple more cicada clips. Just for fun, I turned it up loud to see if it would wake up the cat. BZZZZZHHHTTT. He did wake up, glare at me, and go back to sleep. But more interestingly, the thing outside BZZZZZZHHHHHTTed back. This time, it sounded just like the thing in the YouTube clip. Curious, I tried another one. This was a bit different than the first, with short spurts of zapping.
Computer: BZZHHT BZZHHT BZZHHT
Outside: BZZHHT BZZHHT
Must have been a coincidence, right?
I clicked on a YouTube video of a whole bunch of cicadas.
Outside: BZZHT! BZZHT! BZZHTBZHTBHZBFHDSBFKSDAF%$#@!
Oh my god. I think I've just facilitated an interaction between an insect outside my house and some guy from Georgia's YouTube video. Eat your heart out, Al Gore.