This is such a fun question! I like to think that my theme song is the upbeat brass piece that plays in one of the original promos for The Venture Bros. I regularly do a Jack Black type vocal rendition of this song while I'm running around town for work.
I wish I could link to it, but I've been looking for it for years and haven't found anything. Does anyone know where I can get this song's info? Maybe this is a post for Ask Calecia.
"Altar of Sacrifice" by Slayer. It's one of those songs that since I was 12 would get me primed beyond belief, especially the part where Kerry King dives bombs the tremolo and Tom Araya yells, "Enter to the realm of SAAATTTTAAAAANNNN!!!!!!!!"
Or maybe "Simple Man" from Skynyrd