Have you ever tried/sampled/tasted SARSPARILLA?

The mean, tough cowboy ambles into the saloon and tells the bartender, “Sam, gimme a Sasparilla.” The viewer (like me) wonders, “What is that?”

Sasparilla is actually spelled and pronounced Sarsparilla, but I’ve never been able to find any of it, anywhere, and am wondering if anyone here has had a sip or two of it, what it tastes like, and why has it appeared to have gone the way of the Grape Nehi?

I’m asking strictly out of curiosity, of course. You hear it mentioned on so many western TV shows and movies, you eventually want to find out what it is like, and if it’s worth ordering.