gasi is short for pangasi, a filipino rice wine. it all started when a girl's brother said his favourite drink was gasi but she didn't believe him. since that incident, gasi has become a meme so popular, especially in Singapore.
Jamal: hey dude I'm ordering food, want any drinks?
Dude: Idk
Jamal: Okay then, what's your favourite drink then?
Dude: Gasi