Green’s Dictionary of Slang

gas n.2

[gas v.2 ]

(US black) hair that has been artificially straightened or ‘processed’.

[US]D. Claerbaut Black Jargon in White America 65: gas n. [...] 4. a processed or straightened hairstyle.

In compounds

gashead (n.) (US black)

1. one who has had their hair straightened with a ‘process’ haircut.

[US] ‘Sl. of Watts’ in Current Sl. III:2.
[US]D. Claerbaut Black Jargon in White America 65: gashead n. 1. one who has a processed or straightened hairstyle.
[US]Ebonics Primer at www.dolemite.com [Internet] gashead Definition: someone who has had their hair treated (usually by an amateur), with gasoline in order to eliminate the hair’s natural kinkiness. Example: Look under his hat and you see a gashead.

2. in fig. use, a black person who rejects their racial origins.

[US]D. Claerbaut Black Jargon in White America 65: gasheadn. […] 2. a black person who is a traitor to the pride of his race.