(MONEY Magazine) – Fred Reno of the Los Angeles police bunco squad was working out at a health club when he overheard two people exchanging the password for a clandestine recruiting party for airplane -- the quick-buck pyramid scheme that's taken off across the U.S. Buy in quickly, one urged, because ''they'' were cracking down. ''I was amused,'' says Reno, ''because 'they' is me.'' The fact that pyramid schemes are illegal in most states hasn't stopped thousands of players, who can get socked with civil penalties of at least $2,000 -- and maybe jail. The lure: payoffs of up to $12,000 on a $1,500 ante, as in Los Angeles recently. Other fares: Miami, $2,200; Minneapolis, $250 to $750; and $125 at the University of Maryland. Flight rules: a ''pilot'' antes up, say, $2,000 and induces two ''co-pilots'' to do likewise and recruit four ''crew members,'' each of whom signs up two ''passengers.'' With 15 participants and a $30,000 kitty, the organizer ''pilots out'' with about half the proceeds. The remainder goes to the two co-pilots, who now bump up to pilots, each of a separate planeload needing still more players. The scheme crashes when demand for new players inevitably exhausts the supply. Now fly-by-nighters of all sorts are getting involved. In Missouri, the state attorney general has slapped a restraining order on an Oklahoma- registered operator allegedly pushing several scams, including airplane. All the more reason to just say no.