Is it legal? Should you do it? Do you do it? We're talking about flashing your lights at oncoming traffic warning them that there's a cop just around the bend...
Slacker thinks it’s fine to flash your lights because you’re helping the cop out, essentially. You’re also helping out your fellow drivers. Steve said the “flashy thing” has helped him out in the past,
so he’s not opposed, but he’s forgotten to pay it forward and flash his lights.
What’s the harm? Sure, if someone’s driving like a moron they should get busted. However, if you get them to pay attention and slow down then I see no harm in flashing your lights.