We make ours like milkshakes, but you could sub out the milk for OJ and get a sweeter version. Really you could do anything you want. Here's what we usually do:
1 cup milk
3 HUGE handfuls of spinach (fill up that blender!)
Blend until smooth.
2 TBSP flaxseed (buy from costco. easy huh.)
2 heaping scoops of vanilla protein powder (Also from costco. You have no excuse. Get the purple and silver bag. Not the white container. TRUST ME.)
a frozen banana cut up (I buy 2 bunches at a time, peel them, throw them in a bag all together, and freeze them like that.)
Blend all that up together til it's nice and milkshake-y.
They also double as ice pops in case you were wondering.