Best "Just Kidding" Ever!

The other day, while buying a few more supplies from Walmart for the camping trip, something strange happened. I went to the cashier to pay; she bagged our items (slowly) and I reached into my wallet to pay. Afterwards, she handed the two bags to me and, what I realized a few minutes later, one additional bag. I can only assume that somebody returned a few small miscellaneous items and the cashier accidentally gave me that bag of items. As we walked to my car, I realized I had an extra bag. As I looked into the bag, discretely, I found two pairs of 3 year old sized shoes, some dishwashing detergent, and some colored thread for needle work. The fact that all these items were so random gave me and idea....a wonderful idea! I thought to myself, "Hey man, Allie doesn't know about this. How often have any of us been given an extra bag of stuff we didn't purchase? Probably, never." Ding Ding Ding...a light bulb's silhouette comes over my head.
Casually, as we get into the car, I say, "Now don't get mad at what I'm about to tell you."
"What?", she says curiously.
"I don't think I've ever done this with you around, but I honestly believe that you need to do things like this to keep your body and your "rush" alive and well."
"What did you do?", she once again asks.
"You promise not to get mad?" (I've learned that stretching things like this out make for a much more dramatic climax.)
"Sometimes, when I go to places like this, I take things."
"....You're joking.", she hesitantly says.
"No I'm not. It's not like I'm trying to profit from it. I take random cheap things that don't matter to me. It's not a greed thing."
"....Yeah right, Jeff."
"Fine, look in the bag.", I say as I desperately try to hold back a smile.
She looks into the third bag and gasps. Instead of saying anything, she just stares at me with a "I can't believe you just did that" sort of expression.
"Allie, you have to do things like this!! It keeps you young! Do you really thing I want little kid's shoes and thread? I just grab random things for a rush. Don't get mad!"
As we pull out of the parking lot, Allie, with a very angry expression, jolts open the passenger door and begins to throw out the Walmart bag.

"...Wait...Wait...Wait!! I'm just kidding!"

I enjoyed this prank just about more than anything I've ever done. What a perfect setup.