N-COUNT 調皮搗蛋的人;淘氣鬼;小壞蛋 If you call a boy or a man a scallywag, you mean that he behaves badly but you like him, so you find it difficult to be really angry with him. 調皮搗蛋的人;淘氣鬼;小壞蛋 [informal, old-fashioned]
It's his idea of a joke, I suppose, the scallywag.