Green’s Dictionary of Slang

shank v.1

also shank it
[late 18C use refers to the shank of the leg and was SE; 1990s+ use is abbr. shanks’s pony n.]

1. to walk.

[R. Fergusson ‘King’s Birthday in Edinburgh’ in Poems (1821) 106: If baudrins slip but to the door,...I fear, She’ll no lang shank upon all four This time o’year].
[UK]J. Cameron It Was An Accident 118: ’Scuse me geezer only you point me out the road up some guesthouse mate I can shank to never need no cab?
[UK]J. Cameron Hell on Hoe Street 96: Then I shanked it back up the hotel for a little snooze.

2. (US) to ignore, to overlook, i.e. to ‘walk away from’.

[US]C. Hiaasen Squeeze Me 61: A protracted argument about [...] which of them had shanked the task of shutting the trunk.