Just thought you all would like to file this one away if you haven't already used it: accismus.

It's a terrific example of a type of verbal irony in which there is an affected refusal. Onelook.com uses the word 'coy' here, which seems very appropriate.

Batting her eyelashes as fast as bats out of hell, Brunhilde chirped, "Oh, sweetie, I couldn't possibly accept those free season's tickets to the Carpenter Center musicals!"

I like accismus because there's a kiss in it and that kiss makes it an easy rhetorical term to memorize. But I haven't checked the pronunciation yet, so probably the dadburned kiss isn't even there.