NO! Spartans don't skip obstacles, we overcome them.
We strongly discourage skipping obstacles without attempting them, as it is unfair to others that do attempt them. Plus, aren't the obstacles the point of doing an obstacle course race?
However, if you attempt an obstacle that you simply cannot overcome there is a mandatory set of burpees that you must complete before moving on. This is the case with ALL obstacles. That can add up to a lot of burpees - so try hard to complete those obstacles.
A proper burpee, as defined by Spartan Founder Joe Desena, can be seen here: