Jacob's
Rhyming slang for testicles by means so convoluted as to be vaguely amusing.
Jacob's > Jacob's Cream Crackers > Knackers > Testicles.
The Cream Cracker itself is a fascinating phenomenon. It is a truism of English life that the posher you are the more devoid of flavour the biscuits you consume with cheese.
The Cream Cracker is like a large saltine without any salt. It's regarded as posh by those of the lower orders aspiring to entertain. Higher up the scale is the Carr's Water Biscuit - a double-cooked flour and water wafer originally designed by a Scottish sea captain to be weevil proof. It's about as interesting as sucking cardboard.
The Scots somehow have a monopoly on posh and tasteless biscuits as the very highest social signifier is the oatcake. This is made of oats and water. Yes, that's animal feed to you and I. It has the consistency and taste of a piece of fibreboard and scours the intestines like battery acid.
Ideally this should be consumed with incredibly expensive, well aged, and flavoursome cheese and a stunning port - Go figure