@markdil,
markdil wrote:
I am in disagreement with both my girlfriend and coworker. I made this statement: "They don't call me a genius for nothing." Both pointed out I used a double negative and it was improper grammar. Is it? If it is, how would I reword the sentence? Thanks!
Your girlfriend and coworker are both incorrect.
Double negatives are perfectly acceptable if they are correctly used.
"They don't call me a genius for nothing (=for no reason)" can be turned into a positive statement with the same meaning by removing both negatives
They call me a genius for a reason.