Ha ha... you realize you're going to make me end up hating manual mode now right? You'll win by default and I'll develop yet another tw-tw-twitch.
In that scenario I would meter the grey, set the manual settings, and just shoot. If I was on a 300 or 400mm and wanted to get a face that was looking down a tad or was otherwise in harsh shadow I'd roll my finger over the aperture dial and open it up a click. After I took that shot I would close it back down and continue on.
Baseball is maybe a better example. Grey meter for the field and shoot all night at the same setting - white, black, uniforms and caps it's all going to expose correctly. Now I want some shots of the dug-out... It's in shadow and not lit as well as the field. I look both through the camera and with my eyes at the dug-out lighting (hopefully I did all this before the game) and make an eye judgement at how much I have to open the aperture (for that light - not for uniform color or anything). I open the aperture however much I thought and then check the LCD in case of dSLR or just view it through the EFV in case of bridge cameras (never having to remove my eye! :thumbup: - mine is usually set to display all shots in the EVF for either 10ses. or until I half-press the shutter button again - wonderful for checking every image as you shoot). Anyway that's it. After the dug-out shot(s) I roll it back to the grey metering.
The advantages here are:
While shooting the dugout those 4 or 6 silly incandescent bare bulbs they have hanging down won't throw my cameras' "computer" in the dirt and stomp on it.
While following that pop-fly through the air, past the flood-lights and into the short-stop's mitt - my camera stays set properly for a shot of Hans Wagner's SE-grin just before he throws the batter out on second and wins the world series.

Yeah baby YEAH!
I didn't have to change anything and the camera's light meters weren't thrown for a loop by any of the field or dug-out lights while shooting - the entire session.