International Tea Day (15 December)

"Many tea-producing countries celebrate their product on this day."
Why this day?
"It was created at the World Social Forum in 2004, and the following year the first such day was recognized in New Delhi."
But why this day? And what's the World Social Forum?
"In 2015 the Indian Government proposed a global event to the UN Food and Agriculture Organization, and the first UN Tea Day was celebrated in 2020 on 21 May -- a day chosen because May is the season when harvesting begins in most tea-producing countries."
"But the December date is still used, and has some significance, as the famous Boston Tea Party of 1773 -- a major dispute over tea taxation -- took place the next day."
OK, I give up.
"To the office, where Sir W.Batten, Collonell Slingsby, and I sat a while; and Sir R.Ford coming to us about some business...talked like a man of great reason and experience. And afterwards did send for a cupp of tee (a China drink of which I never had drank before)..."
- Samuel Pepys, diary, 25 September 1660
A first for Pepys, and close to the first for English. The earlier attestations in OED are both from books about China. One (1598) refers to "warme water made with the powder of a certaine hearbe called Chaa".
The other (1655) says that "Chá is a leafe of a tree...called also Tay".
The first actually implying the use of tea in England is from the same year as Pepys, a merchant named Thomas Garway announcing that he "hath Tea to sell from sixteen to fifty shillings the pound".