Green’s Dictionary of Slang

dip n.5

1. (orig. Aus., also dippo) a fool.

[Aus]Bulletin (Sydney) 4 July 9/1: Away in front, railed off from the rest, were the Governor, the Admiral, the Bishop, and a number of lesser lights – ‘dips’ compared with those we’ve named.
[US](con. 1918) L. Nason Chevrons 103: Oh, you clever dip!
[US]L.W. Merryweather ‘Argot of an Orphans’ Home’ in AS VII:6 401: dip, n. A person who lacks good sense.
[Aus]Baker Popular Dict. Aus. Sl.
[US]B. Appel Sweet Money Girl 82: ‘Wise guy,’ he says, like it’s my fault the other guy’s a dip.
[US]Wentworth & Flexner DAS.
[US](con. 1960s) R. Price Wanderers 101: I’d like to sit on your face, you stoopit dip.
[US]A. Maupin Tales of the City (1984) 147: You little dip! Did you come all the way back to fix me breakfast?
[US]Eble Campus Sl. Mar. 5: space cookie – person who is out of touch. Also [...] dippo.
[US]S. King It (1987) 281: Don’t be such a dip.
[Aus]Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Dip. 2. A fool.
OnLine Dict. of Playground Sl. 🌐 dip, dipshit n. an excessively stupid or unpleasant person.

2. (US campus) a bore, a dullard; something tedious.

[US] in Current Sl. (1967) I:4 3/2: Dip, n. Colourless person.
[US]Current Sl. I:3 2/2: Dip, n. Somthing which is dull, mundane or tedious.
[US]Eble Campus Sl. Apr. 2: dip – a dull person.
[US]Eble Sl. and Sociability 59: Derogatory epithets abound, for example [...] dildo, dimwit, dingleberry, dip, donut hole, dork.

In compounds

diphead (n.) [-head sfx (1)]

a fool, an unpleasant person.

[US]G. Underwood ‘Razorback Sl.’ in AS L:1/2 57: diphead n Person considered stupid or socially unacceptable.
[US]H. Rawson Dict. of Invective (1991) 118: The basic dip also can be used as a prefix for constructing such synonyms as diphead, dipshit and dipstick.
dipshit

see separate entries.

dipwad (n.) [-wad sfx]

(US) a general term of abuse; also attrib.

[US] oral testimony in Lighter HDAS I.
Algeo Stud Buds and Dorks 7: Dip [...] dipwad [HDAS].
[US]The Mistress of Math homepage 🌐 So, the DipWad of the day award is actually shared by this woman and her kid. The woman gets it for being stupid enough to give her kid that kind of cash and for being too lazy to take it in herself. The kid gets it for being too stupid to say ‘Oh, I must’ve dropped $5 of it’.
Niagara Falls Reporter 6 Aug. 🌐 Spare me, O deities, from the lunacy of dipwad editors. Many of them are hiring those winsome women you see on TV almost hourly to write about serious subjects.
[US]Mad mag. July 18: It takes a real dipwad to be taking shop class over.