Can anyone explain how this happens?

In what amounts to an epic constitutionality #fail, Senate Democrats may have blown their chances to see their food safety bill signed into law.

The U.S. constitution requires that any revenue-raising bill must originate in the House of Representatives. To honor this provision, the Senate often finds a discarded old House bill, strips it bare, and uses it as a "shell" and passes it back to the House.

They somehow forgot to do that this time.

....

According to Hoyer, this has happened multiple times this Congress, causing severe legislative angina.

TPM

You've got my vote, Mr. Greene

Greene spoke for about seven minutes, and reportedly told Jessica Yellin of CNN, who was in Manning, that his speech was "handwritten on double lined notebook paper."

He began by saying that he is the best choice for the Senate seat, and is "also the best choice for the Image Award next year."

TPM

Shorter Senator Coburn

"Elena Kagan is ignorant of constitutional issues. 

No, I, Tom Coburn, don't know much about Thurgood Marshall. 

No, I, Tom Coburn, don't know much about Ruth Ginsberg."

Longer version here.