Honestly, it depends what med you're taking, how long you've been taking it, and your dose. I was on a high dose of Seroquel for a while and cold turkeyed it (I was in the hospital and the doctor was a dumbass) and that was the worst experience I ever had. I didn't sleep for a week, I couldn't eat for a week. My nurse tried having me take a sip, a single ****ing sip, of orange juice. Nope. Vomited as soon as I swallowed. Also was extremely hot for a minute, then extremely cold for a minute, repeat until being transferred and getting some damn Seroquel in my system.
But then again, Ive been on a low dose of Geodon for a month and stopped it cold turkey myself due to side effects and nothing bad happened.
Overall though, I'd stick with what everyone else is saying and stick to the taper.