Buying two pizzas for 10,000 Bitcoin isn't forgettable to me. Also, the community remembers that day as Bitcoin pizza day. Although that time bought pizza Bitcoin price was low, but for now it's become a huge amount. So this is a memorable history among the Bitcoin community. Another fact of Bitcoin you mentioned on the thread isn't remembering this way we remember Bitcoin pizza day.
Unforgettable history as long as bitcoin exists for the bitcointalk forum, However I don't know if it was the first, but the most famous early purchase was the 10,000 bitcoin pizza from Laszlo Hanyecz, a software engineer who also developed the first GPU miner for bitcoin.
and on May 22, 2010 it is now known as Bitcoin Pizza Day, and back then it was $25 for pizza and paid 10,000 bitcoins worth about $41 and is now a huge amount.