system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do tinted windows almost look like a grid when you wear sunglasses?
gpt
Polarization. Simply put: Sunglasses with polarized lenses align the light in one direction. The tint is an imperfect film that has certain polarizing effects on light as well. When you have the shades on, you’re able to see the alignment of the tinted application. 

Try this with cheap shades. You won’t see anything. Any sunglasses with polarized lenses will show off other polarized items. Even the aftermarket screen protectors on some phones are polarized, you’ll see the pattern as well.