Green’s Dictionary of Slang

a walk, thus an expedition or journey.

1889		Sporting Times 3 Aug. 5, col. 5: There was a gee, there was a buggy, but there wasn’t a punctual Pitcher. So a cheerful guy to Waterloo was the game [F&H].
1977		D. Powis Signs of Crime 187: Guy (Fawkes) A walk: ‘Let’s do a guy’ means ‘Let’s go for a walk’.