Green’s Dictionary of Slang

fun and frolics n.

the testicles.

1960		J. Franklyn Dict. of Rhy. Sl.
1978		Maledicta II:1+2 (Summer/Winter) 117: Place-names turned up [...] Niagara [Falls] = ‘balls’, but in the sense of UK rubbish and US bullshit, not ‘testicles’ – those are bollocks, fun and frolics, and cobblers [awls] – the latter serving for both bollocks and bullshit.
1980		Maledicta IV:2 (Winter) 196: Beecham’s (pills) as rhyming slang on testikills (!) and flowers (and frolics) or fun and frolics as rhyming slang on bollicks are rarer.
1997		Share Slanguage.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.
2003		B. Dark Dirty Cockney Rhy. Sl.