On Sep. 28, 2009, MathOverflow went online, and has almost ten years of almost constant operation, thanks to StackExchange.
There will be an obligatory post observing the anniversary. The board of MathOverflow LLC might hold a toast (with coffee and tea) in observance as well, and they may yet have bigger plans. Until those plans appear, this post is a staging area for people who want to celebrate the forum away from the forum (as in meeting in some locale). For a timely and well anticipated event, starting plans about now seems good.
How do you want to observe the anniversary? And where, and who do you want to invite?
Edit 2019.08.28:
Good news! StackExchange is willing to help us celebrate next month (only 31 days away)!
I need to know how many people plan to show up at the locations to celebrate, so I need a head count. I also need some to volunteer as host/admins to do/delegate what is needed to get the celebration going in your region. I will provide detail about this on Friday.
Right now Alec Rhea, Thomas Rot, Gerhard Paseman, Zach Teitler and Steven Landsburg are my ideas for host/admins. If they agree, they should find my email on my user page and contact me. Other regions will need host/admins: volunteers should also contact me by email, as well as make a post below.
More information will be included Friday in my answer post below. If you have public comments or questions, please comment on my question or answer posts. Remember, the point is to celebrate a fine example of ten years of community action and have fun doing it. StackExchange thanks us for being such an example, and we can thank others during the celebration.
End Edit 2019.08.28.
Gerhard "Where Are All The Parties?" Paseman, 2019.06.21.