Despite the chilly 50 degree temperature, Upton got things hot and bothered on the set. 

"It's the Southwest Patty Melt, and it's one of their classics, but now they're adding a little spice-adding some jalapeños and making it a little bit hotter," explained Upton. "I'm a '50s girl with a little cardigan on, a really sweet kind of a girl. But then I take a bite and all of a sudden, I'm sweating, and I'm taking off all of my clothes and I'm in my lingerie!"

Indeed.