Not just "a piece of wood" but "a very specific piece of wood". It's one of the standard sizes for lumber, and the most commonly used, two inches by four inches profile.
Thinking about writing a Dr Frankenstein fan fic.... Playing Dr with the dead, when science and lightning created monsters, the Dr theorized the missing ingredient was love, so he tries again. Theirs was a love born of science but the Dr couldn't resist Franks flesh!