Is it easy to fake insanity and be institutionalized?

I know in the olden days, they tossed anyone in the nuthouse and didn't give a darn. Now, they used this thing called "science" to get accurate results. If I faked like, delisions, voices in my head, and kept up the act pretty good, could professionals tell I'm faking with all the sophosicted tests and such today? If not, what are the easiest mental disabilities to fake?