The scene involves a tea party hosted by the Passione members to welcome Giorno Giovanna. After a brief conversation, Leone Abbacchio who is despising Giorno's idealism at that time, secretly peeing inside a teapot under the table and hands it over to Giorno to "prove [his] trustworthiness". Giorno then dramatically drank the whole cup of "tea" without hesitation, much to Abbacchio's shock. In reality, Giorno uses the power of Gold Experience to turn one of his tooth into a jellyfish to absorb the "tea" without actually tasting it.
This particular scene later spawned the slang "Aba-tea" (アバ茶 "aba-cha"), which later became a byword for pee drinking/serving fetish.
