To scarper
Rather than being cockney rhyming slang (Scapa Flow = go), I've always thought this derived from the Italian 'scapare', which means pretty much the same thing.
From Cassell's Dictionary of Slang by Jonathon Green:
scarper/scapali/scarpy v. [mid-19C+] (orig. Ling. Fr./Polari) to escape, to run off (cf. SCAPA FLOW). [Ital. _scappare_, to escape, to get away]
scapa v. [1960s+] to go, esp. to run off. [abbr. SCAPA FLOW]
Scapa Flow v. [1910s+] to go, esp. to run off (cf. SCARPER). [rhy. sl.]
scapper v. [1960s+] (Irish) to go, to run off. [SCAPA FLOW]