Puré a pepino in your blender with a bit of water. (If you don't have a blender, you can't cook Mexican food.) Pour the pepino mush through a strainer to eliminate the pulp, skin and large chunks. Add water. I estimate one cucumber requires a gallon of water. Stir in enough sugar to make the water sweet. Squeeze lime juice into the mixture.
In Mexico, everyone buys limes by the sack because lime is squeezed onto everything. If you are ever served something you don't like in Mexico, just ask "¿Hay limón?" and drown it in lime juice. No one will be offended and you might actually like it that way. (If it's pancita, this technique will not work, however.)
A lime sqeezer is helpful when you need to juice lots of limes. I like to try to balance to tastes of the sugar (sweet), the lime (sour) and the cucumber (green). Be sure to use a clear glass so that everyone will think you are a health nut.