A stool sample? That's just weird.
If its a drug sample a urine test or hair follicle test would usually be the test of choice. It's extremely odd for a stool sample to be tested (as nurse girl said) for alkaloids such as cocaine since its excreted in urine within 2-4 days of use. Again as nurse girl said, honesty is definitely the best policy about these sorts of things.
Why in the world would your boss want a stool sample? That's odd.
If this is a drug test, and you've used a drug, the best policy is to be honest rather than trying to get away with lying about something.
Don't no about the alcohol but the coke will its the the in it that will show up