Place your hand palm down on a flat surface (like a table).
Put your middle finger under your palm, leaving your other fingers outstretched. (Kind of like throwing the heavy metal horns, but with only the middle finger tucked in)
You can probably lift your index finger or pinkie finger up alone no problem. Lifting your ring finger alone will probably be hard, if not impossible, as long as you keep your middle finger tucked under your palm.