The diction of mental instability is rich indeed. Already NOOBs has covered daft, nutter, and mad; now comes barmy. The etymology is interesting. From the mid-nineteenth century through the early twentieth, the adjective balmy was commonly used to mean (in the OED’s words), “weak-minded, idiotic.” In due time, this combined in the public mind with barmy, an obscure term derived from barm, that is, “the froth that forms on the top of fermenting malt liquors,” which had been metaphorically, but sparingly, used to mean “flighty” or “excited.”
By 1896, the confusion about the two words was such that a writer in the Westminster Gazette asked, “Should not ‘balmy’ be ‘barmy’? I have known a person of weak intellect called ‘Barmy Billy’.‥ The prisoner‥meant to simulate semi-idiocy, or ‘barminess’, not ‘balminess’.” As he suggested, barmy has since prevailed, no doubt in part to the felicitous barmy army, used to refer to political factions or supporters (a NOOB?) of particular teams.
The weak spot, whose center is off the coast of Brazil, is called the South Atlantic Anomaly, or S.A.A., and it has created a Bermuda triangle of space science. Under its influence, spacecraft can go barmy, losing data, having computer upsets and seeing ghostly images where none exist. (New York Times, June 5, 1990)/Our colleague Ron Charles checks in with Shakespeare scholars, who say Roland Emmerich’s “Anonymous” theory is half-snobby, half-barmy. (Washington Post, October 31, 2011)
notoneoffbritishisms.com 
It should be mentioned that, in most accents of England and Wales, “balmy” and “barmy” are perfect homophones.
You might want to see if barmpot or barm pot occurs anywhere in the US.
It is used in West Midlands and North West England and Scotland to define a silly person or someone acting badly from too much toping.
Clearly, barmpot is ripe for U.S. adoption.
‘Barmy’ has been adopted as an expression of pride by the thousands of England supporters who follow their test (five-day cricket) team around the world. It originated as a derisory insult by an Australian commentator who was watching the antics of the England supporters at a match in Australia a few years ago. The supporters took on the name and they now proudly call themselves ‘The Barmy Army’ whenever they travel abroad to support their team. The ‘Barmy Army’ chant is now a feature of every game that England play
Leeds United fans referred to themselves as Sergeant Wilko’s Barmy Army when the manager was Howard Wilkinson.
Barmy actually derives from the Barming Asylum near Maidstone in Kent, which opened in 1833, makes sense if the first use if the word only dates from the mid 19th century