Green’s Dictionary of Slang

foot! excl.

also foot! foot!
[Fr. foutre, to fuck; usu. addressed to ‘the respectably dressed person who wanders into strange and doubtful bye-ways’ (Ware)]

go away!

[UK]J. Ware Passing Eng. of the Victorian Era 135/1: Foot! foot! Now and again this expression is cast after the respectably dressed person who wanders into strange and doubtful bye-ways.