plumb loco

plumb loco

slang Utterly crazy or insane. ("Loco" means "mad" or "crazy" in Spanish, with "plumb" being used as an intensifier.) Primarily heard in US. This idea of yours is plumb loco. Poor guy went plumb loco after his wife died.
See also: loco, plumb
Farlex Dictionary of Idioms.

plumb loco

Rur. completely crazy. (Loco is from a Spanish word meaning "mad.") You're plumb loco if you think I'll go along with that. All those people were running around like they were plumb loco.
See also: loco, plumb
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

plumb loco

(ˈpləm ˈloko)
mod. completely crazy. (Folksy. Loco is from a Spanish word meaning “mad.”) You’re plumb loco if you think I’ll go along with that.
See also: loco, plumb
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • plumb crazy
  • out of plumb
  • off plumb
  • in loco parentis
  • loco
  • crazy as a bedbug
  • (as) crazy as a bedbug
  • bedbug
  • off (one's) head
  • off one's head
References in periodicals archive
The seven-piece band Plumb Loco I -- comprising of freelance professional musicians from a wide area -- and with members of the band having over 50 years performing experience except for the guitarist, who is not yet 50 himself but who is generally regarded as the best guitarist in the UK, were a great hit and playing music that varied between jazz and rock 'n' roll and even a little of country music as well Another new attraction - and very also very popular - was the Labyrinth Cave which presented a challenging environment, the tight turns and squeeze areas means the system must be crawled through commando style, or those small enough, were almost able to do it on their hands and knees.
PLUMB loco! That's the situation in which Glasgow District Council have to let 26 plumbers take early retirement as of today.
There will also be a birds of prey flying demonstration, vintage vehicles, climbing wall, plumb loco jazz band, Punch and Judy, Howard's vintage fairground, caving experience, dog agility children's entertainment, poultry and rabbit show, trade and craft stands all making towards a super day out.
One of the highlights will be a Spitfire Flypast and another the Extreme Motorcycle display team along with Wild Thyme Cookery Theatre, rural exhibits, terrier racing and the annual sheaf tossing challenge among the day's programme, along with country foods, Sheridan sheep dog, birds of prey flying demonstration, vintage vehicles, climbing wall, plumb loco jazz band, Punch & Judy, Howard's Vintage fairground, caving experience, dog agility children's entertainment, poultry and Rabbit show, trade & craft stands all making towards a super day for the expected hundreds of visitors.