The stiffy is also a
skateboarding and
snowboarding trick. It is so called because you must stiffen your body, and it can also resemble the
male member at its peak of
excitement.
To do this trick get some air off a jump and do an indy. Next bring your legs up so they are (roughly) parallel with the ground. Fully extend your legs as if stretching. This requires some stretching/gymnastic ability. When you are going to land bend your knees and return to your normal stance.