The most people blowing a chewing gum bubble simultaneously is 536 participants and was achieved at an event sponsored by Nintendo of America (USA) in Seattle, WA, USA, on 1 September 2012.
The event was held during PAX Prime, a gaming convention held at the Washington State Convention Center. There were a total of 600 participants who attempted the record. All of the participants were divided into groups of 50 by color coded wristbands, which served as the first counting method. 64 participants were discounted from the total as their bubbles did not withstand the 30-second minimum.
Comments below may relate to previous holders of this record.