Green’s Dictionary of Slang

fart-face n.

also fart-blossom, fartbreath, fart-hammer
[fart n. (1) + -face sfx]

a general term of abuse.

[US] ‘Justinian’ Americana Sexualis 21: Fart. n. [...] Also, a symbol of contempt; a person of little significance. Also, in latter sense, fart-blossom, fart-face, et al.
[US]R. Gover One Hundred Dollar Misunderstanding 170: That fart face done flipflop his Whiteass lid fer sure!
[US]E. Thompson Garden of Sand (1981) 332: Your old lady was tellin me how you stuck up for her when old fart-hammer over there got fresh with her.
[Aus]Tharunka (Sydney) 8 Nov. 27/1: ‘What’ll it be, gentlemen?’‘Horsepiss in a bucket, fartface.’ Oh no, he [is] uncontrollable.
[US]A. Maupin Tales of the City (1984) 82: I have a dog-and-pony show for fartface Siegel this morning.
[US]R.M. Brown Southern Discomfort (1983) 36: That fartface gave me a spiritual ulcer.
[US]S. King Christine 539: What about in the fifth grade when Tommy Deckinger used to call you Fart-Breath?
[UK]K. Lette Llama Parlour 225: Major-Drongo-Dickhead-Ratbag-Fart-Face-the-Third.
[UK]Indep. Rev. 29 May 7: Keep away from my letterbox in future, fart-face.
M.D. Blair Tiara of Thorns 57: I said nothin’, fartface.