Green’s Dictionary of Slang

foolishness.

1785		Comical Hist. of Simple John 6: They tell’d me ye was daft, but I’ll ding the daffing out o’ ye.
1956		C.S. Lewis Till We Have Faces 232: [S]he could laugh loud and drink deep like a man and a warrior, next moment, more madly, answering to Trunia’s daffing.