Jacob's crackers noun the testicles UK Also shortened form “jacobs.” Rhyming slang for KNACKERS;I’mA Celebrity,GetMeOutofHere, December 2004.
[W]hen enjoying a bath with Three Degrees star Sheila Ferguson he [Joe Pasquale] told her; “I’m comfortable with anything, love, but you don’t want to see my Jacobs hanging out”. — TheScotsman, 6 December 2004