Down The What?

Just learned the correct version of a phrase I have said incorrectly for years. I was on a conference call with clients when a woman asked whether the correct phrase was "down the pipe" or "down the pike." I answered that I was sure it was "down the pipe", another co-workers answered "down the pike." Hmm, so we spent a minute googling and sure enough it is "down the pike." Strange. I then asked, "What does that refer to anyway, a channel carrying blood down the shaft from the point of the pike?" (At this point I think I completely weirded out my client). But of course that isn't it. It refers to "pike" as in a large road. Duh. Turnpike.