Generic Variation "Please Select"

We are using variations for tshirt sizes. The issue is the first variation is selected by default so if the user does not pay attention, they could in theory add a medium shirt to the cart, when they really wanted an Xlarge.

Is there a way to add a "please select" option that requires you to select a size/variation?

We tried to trick the system and add a "please select" as a variation, but the problem with this is -- someone could order a shirt and never choose a size.

http://gunyeah.wpengine.com/store/products/military-green-mens-t-shirt/