I was going to click 'never', but then I thought for a moment - 'don't I have to get up to prepare my nicotine gum experiment?' - and had to change my answer.
Just this morning I attempted to play some DDR while eating a scone. As a result, my already-poor typical performance was reduced to abject failure. I wouldn't have predicted quite that level of degradation. Admittedly, the scone was extremely crumbly and otherwise distracting.
Edit to add: I have no trouble with walking and chewing gum at the same time.
Test comment.
That reminds me of a point in my life when I decided to never step on cracks (to counter the effects of people who were not aware), it got to the point where I would not take a downstroke on a bike pedal over a crack, and ended up synching with the sidewalk tiles. Disclaimer: I was at the time, and for most of my thinking life really, caught in a struggle between atheism and extreme magical thinking.
Well, some may question the utility of the poll, but there's no denying that you didn't acquire new data from it. So far, approximately 76% of people here who are diligent enough to browse Discussion chew gum only rarely or never. I'm tempted to try Antisuji's idea and experiment with "Perfect Ten" math on Wii Fit Plus, while eating various foods. And no, the irony of eating food while exercising is not lost on me.
I personally have a tough time filtering out inputs, and find my attention forcibly split between paying attention to nearly everything whether I want to or not. This makes me act and plan more linearly than is optimal, and is horrible for crowded rooms, but otherwise doesn't disable me. Also, I have a strong dislike of the action of chewing gum. I was recently joking about not being able to walk and chew gum at the same time, and I wonder if it might actually have some truth to it? I would like to know everyone's (but especially people with similar filtering issues) habits regarding gum.
How often do you chew gum?
(The poll is in the first comment.)