To make things more intense, exciting, or interesting.
(Phrase first used by Emril Lagasse while cooking.)
Now refers to a song in the Team Starkid
Emril: Let's kick it up a notch! *adds a bunch of spices*
Pincher: "So here’s the choice, Bug! You can go on leading your meaningless existence Or you can take everything you’ve ever wanted...Well, Bug? Whaddya say?"
Bug: "I....I... I think I’ll kick it up a notch!
I don’t care about the Queen or the hive!"
Pincher: "That’s the spirit! Kick em all straight in the crotch!"