ding-dong, n.⁴ — Green’s Dictionary of Slang

ding-dong n.⁴

(US) a stupid, dull person.

1914		Sport (Adelaide) 7 Mar. 5/4: Actions of a madman. Ding-Dong, the local lunatic [etc].
1929		F. Shay Drawn from Wood 74: I’m just a dumb ding-dong [HDAS].
1978		T. O’Brien Going After Cacciato (1980) 14: It’s just that ding-dong, Cacciato.
1983		C. Heath A-Team 2 (1984) 90: We’re not ding-dongs.
1998		Guardian Guide 10–16 Jan. n.p.: Gwyneth Paltrow plays a ding-dong who doesn’t seem to have two braincells to rub together.
		Twitter 11 Apr. 🌐 Any ding-dong can write a book.
2021		Twitter 9 Nov. 🌐 The same ding-dongs who said ‘Bill Barr is trustworthy’ [...] are trying to sell you propaganda on Merrick Garland. Stop falling for this shit!