A trail race to hammer pegs into the ground while blindfolded!
Beforehand, make a trail of pegs that have are only marginally stuck into the ground.
Blindfold a scout and give him a mallet (risk assessment time!)
The other scouts have to direct the blindfolded, dangerous, scout to the first peg. The blindfolded scout must then hammer it fully into the ground, before swapping blindfolds with the next person and repeating.
Could be a patrol competition to see who completes the course the quickest.