Shoes and socks
"I know what I said! I said I'd run around the block buck naked, in broad daylight, if you passed your certification on the first try. You did, you win, I run - happy now?" Jack quietly reaffirmed his intention to never, ever bet against his wife again.
"Oh c'mon sweetie, it won't be that bad." Sylvia was thoroughly enjoying her husband's discomfort. "Who's going to be 'up' at this time anyway?" She just hoped he'd never find out that she'd actually passed the certification test before the bet was made. "Tell you what. I'll even let you wear your running shoes. Socks too, I wouldn't want you to hurt your feet."