JUJUTSU KAISEN SPOILERS:

In ch 75, we get this line from Gojou: "Throughout heaven and earth, I alone am the honoured one."
(I learnt a bit more about this last night and it was very exciting!!)

What he says in the original is "天上天下唯我独尊" (tenjoutenge yuigadokusen)

(I LOVE that translation, btw)

Separately:
"天上天下" = throughout heaven and earth
"唯我独尊" = a bit more literally, can translate to "i alone am revered" (尊 = revered, precious, honoured)

Thus 唯我独尊 by itself is also a phrase for self-centeredness, selfishness, conceit

BUT!
Together, "天上天下唯我独尊" seems to be a phrase from legend, spoken by [Gautama] Buddha (founder of Buddhism) at his birth. He pointed up at heaven with his right hand and down at earth with his left and said, "Throughout heaven and earth, I alone am the honoured one".

In that page in chapter 75 when Gojou says that exact same line, he is pointing at heaven with his right hand, and at earth with his left hand.
It could also be said that that was when Gojou was reborn after his near-death experience.

Another layer to it:
Some people interpret "天上天下唯我独尊" as "I am the only one who can decide my destiny"
This is significant, given when Gojou was born, "the balance of the earth was altered" and from a young age he already had a bounty on his head. https://twitter.com/tellietubbs/status/1344525647780040706

In chapter 72, Gojou is adamant that if Amanai Riko refuses the Star Plasma Vessel transfer, then they don't go ahead with it, and he and Getou would protect Riko's future.
He is determined that Riko is the only one to decide her own destiny.

天上天下唯我独尊

"I am the only one who can decide my destiny"

("Throughout heaven and earth, I alone am the honoured one")