When you slide across the floor real fast and think wow! I'm an Edgedancer! Look at me go!
Also, when you have adopted Sanderson curses so much, your child starts to say Ash's Eyes! Or more recently Scud!
Also, when you try to ingest metal flakes and try to sense your metal reserves for a legitimately long time and think, This metal isn't Allomantically correct.
Doomslug!!!!!