Green’s Dictionary of Slang

chuck-up n.

[SE chuck; i.e. one ‘throws up’ the cheer]

a cheer, encouragement.

[UK]‘Bartimeus’ ‘That which Remained’ in Naval Occasions 96: ‘We reckoned we’d come an’ give you a chuck-up, like, sir,’ concluded another, and [...] they told him of their victory in a three-mile race over a rival cutter.