Dog on Escalator

Shamus O'Connor had just closed down Patty Murphy's Pub and was ambulating his way slowly to the underground subway. Suddenly he was confronted by a huge sign which read: "WARNING! Dogs must be carried on the escalator - Absolutely NO EXCEPTIONS!" Shamus bemoaned: "Bejabbers, and, pray tell, just where is a bloke to be findin' a dog at this unholy hour?"