Green’s Dictionary of Slang

1. (US) a bedbug, a body louse.

1918

Eve. State Journal and Lincoln (NE) Daily News 14 Feb. 2/4: There is a lawsuit on record in Chicago as unique as a country hotel without hootnannies. A hootnanny is what the soldiers call a cootie.

2. (US) an imaginary object; something for which one cannot remember the name.

1929

J.A. Russell ‘Colloquial Expressions from Madison County, NY’ in AS V:2 151: Hootananny: the same as gadget [i.e. the name of anything the proper name of which is not at once recalled].

3. a general term of abuse.

1999

Guardian Guide 3 July–9 July 93: There have been plenty of shows dedicated to holiday hootenannies and hedonism.

4. nonsense, rubbish, anything insignificant; a euph. for damn n., and used similarly, e.g. I don’t give a hootenanny.

1984		Partridge DSUE (8th edn) 568/2: 1963 [...] I don’t give a hootenanny.
1960, 1975		Wentworth & Flexner DAS.
1968–9		in DARE.

5. (US) a party.

1940		Wash. New Dealer (Seattle, WA) 25 July 4: [advert] The New Dealer’s Midsummer Hootenanny. You Might Even Be Surprised!
1964		L. Hansberry Sign in Sidney Brustein’s Window in Three Negro Plays (1969) I ii: Could you conceivably have the hootenanny at another time?
1995		I. Rankin Let It Bleed 76: There was enough booze in the kitchenette to start a fair old hootenanny, but this was a wake rather than a celebration.