Well, I've heard of people putting powdered chlorinated bleach under their fingernails,using salt(but it takes a lot),vinegar or ammonia (not to drink- to put in the pee), but it stinks and messes with the pH and they usually test for pH.I heard of people using Visine, but I'm not sure if that works. You can use plain water but it would have to be warm, because temperature is a dead give away. I dont know. The only sure way is to substitute. Or dilute,aspirin,dilute! (Not TOO much, you can get water intoxication!) Other than that its a crap-shoot.