Here's a new category:
I don't want to learn this the hard way so I'm asking first 
The shelf life of Bailey's Irish Cream?
Their website claims pure taste for two years regardless if it's been refrigerated, just so long as it's been stored at a constant temperature (including room temp). They also claim it's ok to drink so long as it's not lumpy/chunky. They don't specify between opened/unopened bottles though.
Meanwhile, I've got an opened bottle (roughly two-thirds of a handle remaining) of the stuff sitting under the shelf that's five years old. I haven't touched it in probably four years. Most likely it's going down the drain since I'm not interested in getting sick, but I was just curious ...