Euler
Euler is the default form of rotation used in 3D modeling. It exists solely to call your dumbass out for not changing of the default rotation settings to Quaternion, the superior rotation system.
Oh, I'm sorry, did you think you'd be able to make a rotating animation for free? You arrogant piece of shit?? No, fuck you. Nothing in life is free. Your hubris perfectly demonstrates the folly of mankind. You think yourself a god, trying to rotate any object you see fit by 180 degrees, merely ASSUMING it would bend to your will an continue in the direction you thought it might. Wrong, you are, to assume a machine much less a man could read your narcissistic mind and obey the few neurons you have bouncing around your smooth, non-rotated brain.
Your bitch ass probably came here wondering why such a thing would even exist, unable to accept your own failure and seeking comfort in the knowledge of the universe, but look where your curiosity has lead you. Only a mirror stands before you, roughly slanted at a 12 degree angle, reflecting upon your hideous upright form for you to contemplate the shame you bear, unable to continue on the axis in which you sought. Any way you choose to look will lead you right back the path you have already traveled. There is no satisfying ending for the likes of you, only the Sisyphean purgatory of returning to 0 degrees awaits you.