As a non-native reader, I stumbled upon the meaning of "get a serious reaming" and it seemed to be an idiomatic expression for being punished. At least the first Google matches seem to suggest this.
Is this the whole truth, or does this idiom implicate something important besides it?
One of the meanings of the verb ream is
[North American INFORMAL] Rebuke someone fiercely: the agent was reaming him out for walking away from the deal
The gerund form, reaming, is used as a noun to mean a serious rebuke.
Your phrase means to receive a very serious rebuke.
As to its source, etymonline.com give a first use for this meaning as 1950, but does not indicate the derivation. It also notes as a meaning anal sex, dating back to 1942.
There may be a connection between these two uses. In US slang, it is not uncommon to use reference to unwelcome sexual contact to indicate a person was seriously harmed by someone who has power over them, as in
To the extent that reaming might be understood to refer to anal sex (in a pejorative way), it may have migrated to mean being abusively dominated and thence to humiliated through criticism.
The reference is to "ass reaming", a colloquialism for the situation where a superior (officer or manager) "reads the riot act" (look it up -- there are several good references) to an underling.
Of course, "ass reaming" refers to sodomizing someone, in the literal sense.
The idiom is derived from military jargon meaning to ream out the bore of a gun or artillery piece. The act of reaming is a harsh cleaning out of the inside of the gun, with a heavy swab, to remove any residues from previous firings. A "serious reaming" can affect the lands and grooves of the barrel, so a serious reaming is not something you do often, just in cases of absolute necessity.
