Green’s Dictionary of Slang

giggle and titter n.

bitter beer.

1916		Yorks Eve. Post 16 Oct. 5/4: The jargon of the ‘Tommy’ [...] is a never-ending source of wonder to canteen workers and barmaids, with orders for a ‘drop o’ pigs’ or a laugh and titter.’.
1960		J. Franklyn Dict. of Rhy. Sl. 50/2: Chirrup and titter/Giggle and titter Bitter (beer, not fate) [...] has its greatest currency in the theatrical profession. Lupino Lane.
1972		Dodson & Saczek Dict. of Cockney Rhy. Sl.
1992		R. Puxley Cockney Rabbit.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl. 33: giggle and titter pint of bitter.