from Fancyclopedia 2 Supplement ca. 1960
(McPhail) Generic term for a rump convention held at midnight by nondrinking fans during the sessions of a regular convention. The original Sodacon was held at the Southwestercon VI in Dallas by 4e, Dan McPhail, and Marion Z. Bradley in protest against the lack of nonalcoholic refreshment where gin and beer flowed so freely. The Sodacon II was held in Lawton, Oklahoma in 1958, and took its title from the site in the legally dry state where no beverages are available except soft ones. There were 11 attendees. Various small sodacons have been held since at large conventions. The official beverage of a Sodacon is the Atomic Ache (vide Nuclear Fizz) but coffee, lemonade, tea, and ice-cream sodas are also permitted.