It wont make them explode but they will die from the increase of gas which will cause a rupture in the stomach. No, they do not. It is an urban legend based on the fact that seagulls cannot release gases, A Seagull cannot explode if fed on Alka Seltzer. This is just a Native American myth that is scientifically unfounded. It is mostly used in casual talk and should not be taken too serious.