Female led relationships discussion

Hi there, My KH Wife is asking me to get another tattoo. I already have one featuring her name (Mary) on my upper left buttock, and she enjoys pulling the waistband of my trousers down a bit so others can see it. She especially loves showing it off to other women while they talk about their husbands. Now she wants a second tattoo that signifies her ownership and control over me. It should be something she can display to people but isn’t usually visible in everyday life. I need to find or come up with a few options ranging from mild to extreme, which she will approve of. The final design and placement won’t be decided until I show them to the artist at the shop. Any suggestions?