THIS convention was the brainchild of an American, Mike Michaels, and it lends itself to being played in a fairly simple way.
Why is it useful to make two-suited overcalls?
When the opponents open the bidding, it is a winning strategy to try to make their lives as difficult as possible, either pushing them higher than they would prefer to be, or just stopping them from declaring. While this can be effective with one-suited hands, there is even greater potential when holding a two-suited hand since there is now a much better chance of finding a fit in at least one of the long suits. It is also helpful to show the two-suited nature of the hand as quickly and efficiently as possible.