Dear __________,
You really know how to surprise someone! When I walked into the break room I was completely caught off-guard. I was not expecting to find the group of you gathered there singing the birthday song, with balloons, a banner, and a beautiful birthday cake. Thank you so much for organizing this for me. I feel so lucky to work with such a great group of thoughtful and caring people.
Sincerely,
(YOUR NAME HERE)
