I used 'the look' when I worked in Middle School, having perfected it with my own kids. I truly believe it's why I got the respect and love from 'my kids' while I worked there. "Uh-oh, Mommy R. is pissed..."
It's become such second nature that my son, who will wave me off when he's on the computer, tries to not look at me because once he does, he knows he'd better move it. I'm not even sure anymore what 'the look' looks like
I just know it's there based on my kids' reactions.
Part of the shoutbox convo was 'how does one get 'the look'?' It is really just a matter of a stoic, no-nonsense stance; no backing down, no relenting or giving up, no shouting or getting crazy(but making the receiver of it think you're gonna blow anytime soon). There were times I'ved had to stifle a giggle and keep 'the look' going and other times keep myself from going postal.