I am particularly fond of the unofficial “ food stamps for crack “ program....
This works with chain migration. "Family-sponsored" green card holders get food stamps, especially if they have kids. They know lots of illegals (and their friends too) from their home towns south of the border. Food stamps are easy to sell, and they don't feel guilty about doing it.
I am not making this up. I reported one of the green card holders to "La Migra" but they were not interested. I don't think the person selling the food stamps was involved with illegal drugs, but after the food stamps go into the black market economy, who knows.