I'm not sure why I like this movie so much.
I first saw it when I was 10; my uncle and I hung out alot when I was younger, and one of his favourite tv channels (on his super decked-out satellite packege, lol!) was this channel that seemed to only show non-stop grade z exploitation flicks.
I remember watching this one, thinking how hilarious it was, but not knowing the name of it.
Years later, when I was fifteen, I stumbled upon it again, finally hearing the name, and buying it later.
The plot has already been explained by others, so I'll just state my opinion of this movie;
It's alot of fun. It's not a technically "good" movie, heck, it's not even a good sexploitation flick (most of my friends refuse to call it sexploitation; not enough sex going on :P), but it just comes together well. I don't understand people who say it's boring; it's so bizarre, so strangely handled (half of the cast take it way too seriously, the other half don't take it seriously at all) that I don't see how you could be bored. And all of the women in it are really hot; which is a nice change from some exploitation flicks I could mention. (Deadly Weapons, anyone?)
All and all, I think it's very worth buying. Always cheers me up. :)