depends on what kinda lab. If it's a scientific lab that requires precise numbers, or there is a small range of number that could be truthful, then I don't see a good reason to lie/cheat because you'll probably get busted.
Also, most schools (I'm assuming this is college) charge a lab fee, so you might as well get your money's worth and gain the experience, seeing as how it goes with the rest of the school fees and you're going to be charged double the lab fee once you add intrest on it.