Peanut butter wrench
A peanut butter wrench is a a single-ended socket wrench used in cycling to tighten cranks and the wheel nuts on track bicycles, particularly a 15 mm wrench made by Campagnolo. The wrench is apparently the right size and shape to scoop peanut butter (a fairly cheap energy food for track cyclists) out of the jar. The traditional high quality of finish on Campagnolo tools makes this a less unsanitary procedure than it might be with lesser tools.