By gum. listen to your mother!
As we all know by now, any criticism of chewing gum can get you into a sticky situation (ho ho). But didn't your mother always tell you not to swallow gum? Sure, you probably didn't want to anyway, and it would probably just break down in a few days anyway, right?
For the most part, this is what happens. But occasionally, as mentioned here, some seriously horrible crap can happen to the gum gulper. Scientific American quotes a report which describes:
'three children suffering from gum-based gastrointestinal blockages, two of whom received gum as positive reinforcement for good behavior and regularly disposed of the treat by swallowing it. In both cases the children became constipated, as the gum snowballed into a substantial "taffylike" mass that required extraction. In the third patient, a girl just a year and a half old, four coins were found lodged in the esophagus, fused into a single blob by a wad of chewing gum.'
Well, that's just lovely. One more reason to ban the stuff, eh?