Ill effects from swallowing a mouth full from a day old cup of chewing tobacco spit? was half asleep and accidentally took a drink from the wrong cup.

No more ill effects: generally than some stomach upset and heartburn. You are actually always swallowing some of this mess. I would hope that this experience would tell you that this is not a habit you want to cultivate, and you quit before you end up with head and neck cancer, heart disease and other complications of chewing tobacco. Your teeth get stained, your breath stinks and it is altogether unattractive.