I'd apologize for ingraining the theme to the '90s X-Men cartoon in your head, but 1.) I'm not actually sorry; 2.) it was probably rattling around in there anyway; and 3.) this a cappella rendition is pretty entertaining.
The video comes from The Warp Zone, the nerdy sketch-comedy group that previously released a cappella versions of the themes to Darkwing Duck, Captain Planet and Game of Thrones, among other shows. So, if you've seen any of those, you know what you're getting here -- namely, a fun take on a tune that most of us know by heart, delivered in an earnest fashion. Heck, they even do appropriate costumes (well, T-shirts, in any case), slash claws, toss playing cards and ... make a microphone tremble?