When an "influencer" (usually Instagramwhite girls/fuck boys) posts a picture of the place they're at that includes some body of water that looks very blue, and very beautiful. Fact: this phrase was invented by Cody Ko, in his video titled "QUIT YOUR JOB AND TRAVEL FOREVER!!".
Person 1: "Look at this hot girl's Instagram post. 2 weeks in Greece! I wish I was her."
Person 2: "Yeah look at that blue ass water. Now I feel like shit."
The most glorious thing to ever bless the earth since Mother Teresa. It is an ass so beautiful that all other asses bow down to it. It should be treated with the highest of care and shown to all friends. It is first in its ass.