Round 'em up and march their asses to the border crossings, Trail of Tears style. Feed them beans and rice and water them... They will be gone in a month at littlecost to the taxpayer... AND THEY WILL NOT WANT TO EVER COME BACK.
Perhaps they will tell their friends not to bother.
Then if we did that the Mexicans would have to deal with them seeing as they let them into their country to get here.
Watch Mexico put a stop to it right away if those illegals had to stay in Mexico.