I put together our new bench, and then am stripped naked and put over it

Shilo says, "She was out the day I finishing putting together the  spanking bench, that had arrived in a big box, parcel post.
 She arrived home. I said, "Okay, come and take a look." 
She did, and grinned...evilly, and said, "Get naked, and get over it, while I gather some implements."
 Some hours later, my butt was red, sore, and throbbing.