It's generally frowned upon.
11/1/06 WT
Furthermore, we can show how deeply we respect the sacred nature of our gatherings by the way we dress. Our appearance with respect to both our clothing and our hairstyle can do much to add to the dignity of our meetings. The apostle Paul counseled: “I desire that in every place the men carry on prayer, lifting up loyal hands, apart from wrath and debates. Likewise I desire the women to adorn themselves in well-arranged dress, with modesty and soundness of mind, not with styles of hair braiding and gold or pearls or very expensive garb, but in the way that befits women professing to reverence God.” ( 1 Timothy 2:8-10 ) When we attend large conventions held in open-air stadiums, our dress can be appropriate to the weather conditions and still be dignified. In addition, our respect for the occasion will lead us to refrain from eating or chewing gum during the sessions. Proper dress and behavior at our gatherings honor Jehovah God, his worship, and our fellow worshippers.
The paragraph specifically mentions conventions but it also applies to regular meetings. I chew gum all the time and I never catch shit. No one really cares except the uber pious fucks
