Codswallop could have a past. "Codshead" for stupid fellow appeared in print in 1556 (OED). Wallop has many meanings; codswallop may yet be found in old writings.
Shamble, meaning to slaughter or cut up, turns up in print at the end of the 16th C (in time for the English renaissance and Shakespeare) but shamble meant a table for slaughtering meat by 1305, so shamble for slaughter is prob. medieval. Its earliest meaning (ca. 825 AD) was footstool. Later it was a table for counting out money. It is another word with many meanings, so a good candidate for slang expressions.