# What does “hit me like a two-by-four” mean?

What does this sentence mean?

This observation hit me like a two-by-four

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2×4:

Image courtesy of Wikipedia.

Edit: Wikipedia has since corrected itself that this is indeed a 2×6, but you get the idea.

Oh, and the sentence as a whole means that the observation was a big surprise or a great shock; an aha experience or a eureka moment; an eye-opener.

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From the source: “ The nominal size is 2 by 4 inches but the actual size is 1.5 by 3.5 in (38 by 89 mm)” – F'x Jan 20 '11 at 9:47
Though, an actual hit by an actual 2x4 is more of an eye-closer... ;-) – Jürgen A. Erhard Jan 20 '11 at 10:47
@Jasper: I agree, it looks more like a 2x6 to me (1.5 x 5.5 in) – John Satta Jan 20 '11 at 12:12

A two by four is a common format for a piece of wood:

A length of sawn wood of cross section 2 inches by 4 inches, most often employed as structural framing lumber (dimension or dimensional lumber).

"It hit me like a two-by-four" means that you've been hit pretty hard.

In this context, the author uses it as a simile to convey his state of shock after reading the analysis he quoted. He felt that it explained so well why Asians were often stereotyped as good in science and math that it stunned him.

He explains this further down the page:

I hadn't known about the 1965 Act, and its existence and the above analysis just instantly explained so much so well and without reference to Asians somehow being magically different

In other words, he was really surprised by the quality of the explanation.

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Maybe not quite 2x4, but close enough ;) (This is supposed to be humourous, please don't vote it above the real answers!) – Benjol Jan 20 '11 at 9:59
Isn't that a standard-issue cluebat? ;-) – Jürgen A. Erhard Jan 20 '11 at 10:48

"Two-by-four" is a standard size of wood used in the UK building trade.

So it means a piece of wood with sides of two inches and four inches.

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This may have derived from the story about how to handle Mules. "First" (clobbering mule with 2x4), "you have to get their attention."

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