live one

Possibly an allusion to hooking a particularly lively fish on a fishing line.

• IPA^(key): /ˈlaɪv wʌn/

live one (plural live ones)

1. (informal, idiomatic) Someone who is easily fooled, victimized, or ridiculed.
   • 2009 January 7, Bill Virgin, “In 2009, it's all about green”, in Seattle Post-Intelligencer, USA, retrieved 3 Feb. 2009:

     There's green as in greenhorn, meaning inexperienced and gullible. Those with a pitch to sell are going to spot a live one—in this case government with dollars practically falling out of its pockets—coming from miles away.

2. (informal, idiomatic) Someone who is eccentric, nonconformist, or otherwise peculiar.
   • 1997 September 13, Charles Placker, “Ministry of happiness denies the crucifixion”, in The Victoria Advocate, Texas, USA, retrieved 3 February 2009, page 3D:

     They've got a live one in the crowd, he's scary, he looks dangerous, demon possessed, he doesn't know who he is, he speaks in strange voices.

   • 2004 September 28, Polly Curtis, “HE Diary: Howells has landed”, in guardian.co.uk, retrieved 3 Feb. 2009:

     We've got a live one. Kim Howells burst on to the scene last week with his first foray into university politics as higher education minister. The man best known for labelling the Turner Prize "conceptual bullshit" was not sounding very on-message. In a departure from his prepared speech on the launch of an NUS information campaign for would-be students, Howells started, well, rambling.

3. (informal, idiomatic) A person, thing, or situation which is particularly interesting, noteworthy, or urgent.
   • 2007, Tom Lawrence, "Area DUI crack down reduces arrests," Black Hills Pioneer (South Dakota, USA), 2 Jan. (retrieved 3 Feb. 2009):

     "We got a live one here," he said as he speeds up in pursuit of a car.

• When used in the singular, almost always preceded by a.

• (someone easily fooled or victimized): chump, dupe, mark, patsy, sucker; see also Thesaurus:dupe
• (someone who is eccentric or peculiar): head case, kook, nut, oddball, weirdo; see also Thesaurus:strange person
• (person, thing, or situation which is particularly interesting, noteworthy, or urgent): real McCoy

• “live one”, in OneLook Dictionary Search.

• Evil One, veniole