The Public service announcement for the day is
When using a pressure washer to clean an aluminum stock trailer that has floor and walls covered with 6+ inches of dried cowsh*t, it is best not to begin operations from the inside. Dried cowsh*t turns liquid, very, very quickly. And tends to splatter... I would go so far to say ricochet.
The results are not pretty, if you don't believe me, ask my bride!