Family Barbecue

We're going to my sister-in-law's for dinner on Saturday. Being the polite people we are, we offered to bring something. You know what she asked me to bring? A pan of Rice Krispie Bars (Busy and Didder are laughing, aren't you?). I have no doubt SIL was thinking, "Hobbitsister can't cook (which isn't an insult because it's absolutely true - Christmas at her house is a huge fancy sit-down dinner; Christmas at my house is ham sandwiches), so I'll have her do the easiest thing I can think of."
So I have to bring a pan (not little blue packages) of Rice Krispie Bars.
She could have said cake, or brownies, or lemon bars, or poppyseed bread. But no - she said the one thing in the world that I absolutely cannot make.
I tried a few years ago. "Hey, Erma, do you want to help me make Rice Krispie Bars?"
Erma: Make Rice Krispie Bars?
Me: Yes, do you want to help?
Erma: What do you mean make?
Me: You know, make - mix them up, in a pan, on the stove...
Erma (incredulously): You know how to make them?
She had always thought that Rice Krispie Bars came in a box, and now Mom had somehow acquired the top-secret recipe - like making Oreos.
So we made them, and (thankfully) for the first time in my life they actually turned out. The next time I tried them, it was again a failure, and I haven't tried them since.
And now I have to make them for Saturday. Do you think SIL would know if I just unwrapped all the blue packages and crammed them into a pan?