If a guy calls his girlfriend " GIG " is wrong calling because " GIG '' is using only for a guy who gets pay from a women to take her out to eat, to travel and also to have sex with her.
I see Lao and Thai guys call their girlfriends " GIG ".
GIG means " Phu Sai Bum-ler " in lao and thai. We call " Phu Gning Bum-ler " as " So-Phai-Nee "