If you are a liberal these days, you are losing most arguments that are based in facts. Liberals therefore are resorting to the ad hominemattack, which involves attacking the people they oppose instead of their positions.
For example, I say “2+2=4″, to which a liberal responds “No, 2+2=5″. I demonstrate by handing her 2 $2 bills that 2+2=4 and ask her to explain how she can buy a $5 coffee at homosexual supporting Starbucks with just $4. She then explains “Shut up!”. I then walk with her into the Starbucks and ask her to buy herself the $5 coffee with the the gift of my $4 dollars. The Starbucks droid, a free-market capitalist, declines the opportunity to let our liberal buy her coffee at a discount. After our liberal has a little nutty, she turns to me as says, “You are a poopy-head.”, thus crushing me in the iron jaws of her logic and winning the argument. MSNBC has a party.
A similar thing on a larger, and far more vicious scale, happens when conservatives make a pro-life argument. Liberals resort to the ad hominem and call us racists.