Sarsaparilla syrup
Sarsaparilla syrup would best mask the taste of an oily substance.
No amount of water can mask or clean a drug screening.
Mask the taste with other flavours/spices
No. Bane's mask is part of his system for delivering the drug "Venom" to his brain.
A liqueur. They are sweet and mask the alcohol taste pretty well.
It would seem like it is not true, but if coffee is bitter, adding a little salt will mask the bitterness and the coffee will taste sweet.
No, oil will only mask the wonderfull taste! marinade your meats before putting them on they will taste great!
Drug stores
No, there are no such masks for retail sale. Your best bet would be to find a cosplay helmet and fit it to a regulation mask.
Mask
Hydrogen peroxide is not typically effective in helping to pass a saliva test. Saliva tests are designed to detect recent drug use, and hydrogen peroxide is not proven to mask or interfere with drug metabolites in saliva. It is always best to refrain from drug use if you need to pass a drug test.
The rabbit may be introduced to certain minerals that affect the taste of the water. If he finds the taste objectionable he will not drink, if he does not drink he will not eat (called going off his feed). To help keep the taste of the water the same (and keep your rabbit eating) certain electrolytes can be added to the water regularly OR a small amount of flavored jello can be added to mask the taste and therefore mask the taste when you are traveling (showing) your rabbit.