So I did it! And guess what, it wasn't very hard to do.
Scrapbook paper, Empty bottle, Contact paper, Scissors, Full bottle!
Trace your empty bottle's cap on a piece of scrapbook paper
Cut it out a little smaller than your tracing and make sure it fits in the cap. Trim if necessary.
Write a little note on the circle. Cut out a small piece of contact paper. I used contact paper to make the message waterproof and to securely stick to the lid.
Stick your circle message side up to the sticky side of the contact paper.
Trim the contact paper into a little larger of a circle and stick into the lid.
Won't your special someone be surprised when they open up their drink during the day?