Excuse my younger self's gothy inclinations, but this one always got me pumped in the mornings. Made me imagine some victory banquet in Hell...
Most classic (read: non-death or guttural growling-based) metal also tends to put me in a good mood. Black Sabbath, Ozzy, Dio, Iron Maiden, Judas Priest, etc.
This is the 1st track on Ringo's Rotogravure, which I own on vinyl. I can't help but get a big stupid grin every time I put that one on.
No one can convince me that this isn't the best anime opening ever.
This was already adorable in English, and, somehow, the German version does it even better. It probably helps that I'm amazed this song even exists, and that it isn't a cover.
AND THE MOST STUPIDLY HAPPY OF ALL;
Come on everypony, smile, smile, smile! Fill my heart up with sunshine, sunshine! ^^