First off, hopefully the tiny little Joker reference is already enough to be entertaining in some way. Secondly, I want you to know that hey! Even if you just started your day and it's already not going so well, I believe things will get better soon. They always do. The same goes for if it's the middle of the day, maybe something someone said ruined your mood, maybe something unfortunate happened, either way, I know you'll be able to push through it. You're a very strong man, John, stronger than you might think you are right now.
Right now I want you to do your best to relax a little. You should take a few minutes, even if you're expected to be doing some work. You deserve it. If you're feeling stressed out, maybe try doing something that'll distract you, like play a game you enjoy, listen to music, etc, etc. Even if you can't do any of those at the moment, there's always alternatives and you always have your mind, right? Anything that'll clear your mind a little will absolutely help.
And just so you remember, coming to me is always an option. I would never mind listening to you if you want to rant, get things out of your mind, whatever you may need me for. I'll always be here for you. :)