All admissions departments specialize in sniffing out bogus extracurriculars on applications. They read between the lines on everything, and they have other sources to cross-check some items. If there's any real doubt in their mind, they're going to hold it against you in a big way.
If you exaggerate a little, that's probably common. If you really take major liberties with the truth, you're playing Russian Roulette with your chances of admission.