Tania Hennessy is a scientist who sells beautiful visual illusion necklaces over the internet under the name Aroha Silhouettes.
The one pictured is a Penrose rectangle, a type of impossible shape of which the Penrose triangle is the most famous (and you can buy one of those too!).
However, there are many other impossible objects you can get as necklaces or earrings, all designed as striking silhouettes.
And if it’s not for you, you could always buy one for the girl in your life.
How often will you ever have the opportunity to use the line “No honey, I wasn’t staring at your breasts, I was marvelling at how a relatively simple collection of edges can demonstrate the conflicting constraints of the visual perceptual system”.
Obviously, make sure she’s wearing the pendant at the time. It’s not an all purpose excuse.