Tricep exercises to do in the office?

CostaRica120

Hi all,
Does anyone have suggestions for tricep exercises that can be done without weights and without drawing too much attention in the office?
I like to do other little exercises at my desk throughout the day, but haven't thought of anything that would work my triceps...

Thanks!

Michael190lbs

Dips on a chair, push ups keep elbows as close to your body as possible