It's the one day of the year to be thankful for that person who keeps everything working.
Say what you will, but if the sysadmin decides to halt all the servers, no one will be getting anything productive done.
Devs, DBAs, salespeople, CXOs; the whole gamut of the workforce should be thankful that the unappreciated system administrators let them use their precious network.
Therefore, it's a hearty thank you to all of the sysadmins out there, and today is a day for you. I'm glad you're handling the support calls from the general workforce instead of me.
But rather than going into neckbeard-cliche territory myself, I'd rather just let the song below do it for me.
Remember, they are probably caffeine addicts, so a coffee or slab of coke is going to be appreciated. Or, if you want to be a superstar, offer to tidy up the patch board — go on, I double dare you.