Some years ago, a group different from the one I worked in invited me to "volunteer" to help them with serious problems they were having with their product. They asked to "borrow" me for one week so that I could magically resolve all their issues. I wasn't really that familiar with their product, and I certainly didn't know how it worked internally, so I didn't think I could actually be much help given just one week. But they kept insisting that I "volunteer" to help them, until I finally wrote,

I have a lot of vacation days and I'm not afraid to use them.

That one line catapulted me into thermonuclear device territory.