I've been keeping it in for too long. Let me tell you exactly how nuts this sign (on Grant Street, downtown) makes me.
A minor source of annoyance is the use of a noun (gridlock) as a verb. But this is pretty common and I'm a relatively frequent offender, so I suppose that can be forgiven.
Then we have the double-negative paradox. There's a negative command "Don't Gridlock" positioned inside the international restriction symbol (also negative). Taken together, if we apply the same rules to language as to math (as I think we must, dear readers), this literally means "you are not permitted to not gridlock". Oh, okay. So...I should make every effort to produce gridlock, then, right??
And on top of all of that, after two strong commands ("don't" and the restriction symbol), we're treated to a polite (I suppose that's why it's in a lovely script font?) request. Please? Oh...well, if you're just requesting it, then I'm free to refuse...
Someone bring me the head of that sign designer. Please?