John McCain wants to be your friend. He regularly and repeatedly addresses audiences as “my friends,” Paul Collins writes for Slate, calling the habit "the most mystifying verbal tic of any politician since Bob Dole." FDR and William Jennings Bryan shared the habit, but in recent years it's been co-opted, perhaps because of its old-timey feel, by conservative pundits like Rush Limbaugh and Pat Buchanan.
The phrase's roots lie in classical antiquity, but its “less nuanced” use by the likes of Limbaugh and Buchanan makes its “implicit aggression” more overt, Collins notes: “Generally, when someone not personally known to you addresses you as 'my friend,' the safe assumption to make is that he is not.” (More John McCain stories.)