In North Carolina (Nash County), we use the word “Coke” or “drink” generically for most soft drinks. The words “soda” or “pop” have always sounded strange to me, so I never use them. While living on Cape Cod, I use to hear “tonic” as being synonymous for soft drink. According to Strange Maps, whether you perceive soft drink as soda, pop, or something else is “the basis of an article in the Journal of English Linguistics (Soda or Pop?, #24, 1996) and of a map, showing the regional variation in American English of the names given to that type of drink.” More discussion can be found at Strange Maps.