Green’s Dictionary of Slang

(S.Afr.) a braggart, a boaster, a ‘blowhard’.

1987		Frontline Apr. 23: What sort of person gets caught up in drag racing? ‘The windgatte,’ answers Mick [DSAE].
1992		P. Slabolepszy ‘Return of Elvis’ Mooi Street (1994) 314: You can still outperform some smart-fancy windgat just outa’ school.
2003		‘SA English’ on Joburg.org.za 🌐 Windgat (pronounced vint-ghut) – This means a show-off. Taken from the Afrikaans, it literally means ‘wind hole’ and refers to a show-off blowing his own trumpet.