Watercolour tattoos are beautiful, right? But if you don't want a commitment, you can re-create the look by using food colouring and any waterproof liquid eyeliner you have handy.
Practice a little by tracing geometric shapes (or whatever design you like) on a piece of paper. Then, using different brushes, pat on the food colouring. It should wash off in the shower using soap, water, and a little exfoliation. Also, if you're allergic to food colouring, maybe sit this one out? And always test a small patch on a hidden part of your body before trying out trends to see how your skin reacts!
Let us know in the comments if you'd give this a go.