A deliberate insult said to a person's face by a Southerner who is thought to be giving high praise, but is in fact thoroughly insulting the person. The slam is said in a heavy Southern drawl so as to fool the person into thinking you are stupid.
Example 1:

Upon seeing a woman approach wearing a hideous dress:

Southern Slammer: "Where eva did you get that dress? I simply must know. It takes my breath away!

Loosely translated: "That is the fugliest dress I have ever seen. I want to know where you got it so I can avoid that store like the plague!"
by Loxi July 19, 2009
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