Okay, I've played Psychonauts numerous times before and I never remember this happening. It's driving me nuts and I need to know if anyone else hears it too.
When wandering around the campgrounds I noticed that every so often I heard the mouse click sound. I promptly turned off the mouse click sound in Windows, but I kept hearing the sound in game. After a bit longer I noticed that it only happens when wandering around the main campgrounds. It does not happen in cinematics, when people are talking, or in different areas.
Is there just a part of the music that sounds like a mouse click that I never noticed before? This is making me feel super crazy.
Update: I quickly made this video to show what I'm talking about.
Update 2: I didn't think it was the grasshoppers, but apparently it is. After looking up more videos I noticed it happened in all of them at some point. I definitely don't remember that sound being so loud and annoying.