So far, I have these
"Well I went through X and it worked fine for me!"
"Well I've paid taxes for years and I don't see any gun aimed at me!"
"We just need small government. Anarchy is too extreme!"
"But there would be just chaos with no government!"
"Anarchy requires everyone to be saints!"
"But we'll get invaded!"
Anyone got one they'd like added?
"If people are allowed to own deadly weapons, they'll just go around murdering each other."
In case you haven't covered this one before:
"Without the government, how will we deal with market failures?"
"But you anti-government types still use the roads! You're hypocrites!"
Then there's the bit where they complain about monopolies as a failure of the free market, then turn around and defend government monopolies (power, roads, etc.).
You could probably pick some from here:
http://www.dailykos.com/story/2012/03/29/1078852/-75-Ways-Socialism-Has-Improved-America
"Capitalism may have worked fine in the 19th century, but now the population is bigger!"
As if the same people would have been for it back then.