Song describes how four Irishmen called Hogan, Casey, Murphy and "me" spent all their money drinking beer in a pub with an ex-Highland soldier called Patsy Callaghan, who had had his legs shot off from under his kilt when at war. To recover their solvency they got Callagahan drunk, then removed his wooden legs and false teeth, pawned them, and left Callaghan literally legless on the pub bench. His plight, depicted on the front cover of the songsheet, is regarded by all as very funny, though the speaker can't help wondering (in the words of the chorus) "What will poor Callaghan do?".
Portrait of Michael Nolan in character on front cover