Instead of a Staff Appreciation Day, maybe the staff who feel they need to be appreciated need to take things less seriously, such as insults from random kids online. Plus, Staff Disrespect is against the rules, so if someone is actually disrespecting you, handle it the correct way.
And if you reaaalllly need to feel appreciated, just go find a random stranger online and be nice to them, most people are pretty nice back. And if they aren't nice back, they are a random stranger so who cares, go find a new random stranger.
This can apply to anyone, not just staff :)