Gay: "I've heard many offensiveexpressions in my lifetime but none as bad as 'damn straight' it's just annother way to bring the gay man down"
Straight: "ummm will you suggest an alternative?"
Gay: "how about...... damn gay!"
"Damn gay" means the exact same thing as "damn straight" (i.e., word up, that's right, etc.), except that the term "damn gay" can be easily used by homosexuals or referring to homosexual actions, etc.
Situation A)
Lesbian I: Holy crap, she is so hot!
Lesbian II: Damn straight! Only... not... *awkwardness*
versus:
Situation B)
Lesbian I: Holy crap, she is so hot!
Lesbian II: Damn gay! *note lack of awkwardness*