What effects does welfare, illegal drugs, food stamps, have on the GDP?

From what I understand about the illegal drugs, the "product" that money is spent on never gets counted. But does welfare and food stamps have an effect as well?

drugs should be legal

That's why we need a flat sales tax, and do away with income tax.

The drug dealers, pimps, whores, criminals, imbezzlers, will pay their "fair share".

The more you spend, the more you pay.

Makes sense to me.