Unless they're female.We generally do not like to call our Presidents by their first name, for reasons of respect (but this does not really apply to the legislative branch all that often).
Trust me, if Clinton had been elected, she still would've been "Hillary".
If Palin is ever somehow elected, she'll still be "Sarah".
The Makeout Hobo is real, and does indeed travel around the country in his van and make out with ladies... If you meet the Makeout Hobo, it is customary to greet him with a shot of whiskey and a high five (if you are a dude) or passionate makeouts (if you are a lady).