If it doesn't take gum years to digests, what actually happens when you swallow gum? Basically nothing. It may take a bit longer for the gum to pass through your body, but the gum will pass right through and exit as waste. That's it. It's still not a great idea to swallow gum as blockages can take place, but rest assured, the gum won't be sitting in your stomach for the next 7 years.
For more detailed information check out:
Fact or Fiction?: Chewing Gum Takes Seven Years to Digest