I found this pin this morning on residential property outside Fort Chaffee. The 5th Armor was stationed there in the early 50,s; But the pics of pins for them that I have found are very different. If anyone has info of the unit that wore this pin please provide.
Okay, took a while but I have some info on this. "Do Something" was the regimental motto of the 80th Armored Regiment, which was later redesignated the 80th Tank Battalion. It's history runs back to 1917. I can't find this exact pin anywhere with the exception of one example on Ebay UK, but I'm going to guess your pin goes back to WWII or thereabouts.
Here is a neat website that is indispensable for doing Heraldry research. I used it when I had to research in order to purchase items for military units when I used to be in the Army :