How do you prevent a rocket from flipping over and over on its own while in space away from anything that could possibly affect it motion wise?

[Omnifarious]

I may be a noob, (only a few hundred hours, and have only gotten to the Mun, Minmus, and Duna) but I keep getting this strange thing in all my rockets where they decide to start rotating on their own when I disable SAS while in space, (out of the atmosphere of any planet) and then they just build up momentum  in a matter of 60 seconds until they're spinning like a fidget spinner. Any idea why? I am missing something very obvious about space travel? Am I have a stupid? Like when someone says there's no gravity in space when someone's in orbit? I feel like I'm having a stupid.

[Boris-Barboris]

Usual suspect. Press Alt+X.

[Kerbal101]

@Boris-Barboris Its not Alt, its "Mod" (+X)   Which is Alt on Windows, right Shift on Linux and Option key on Macs

[Mako]

@Omnifarious This can occur if you have some parts that are clipped through other parts on your ship. Sometimes the clipped parts can induce unexpected phantom forces between parts which can cause rapidly accelerating rotation of the ship to occur.

If you don't clip parts but still experience the rotation, I would start to suspect a mod might be causing your trouble.

[Omnifarious]

Thanks for the tips everyone, yeah, I assumed it was on my end. I had various science equipment squished into a bay I put on all ships. With the bay removed, my craft no longer fullfil their desire to be a fidget spinner. 

[klgraham1013]

I suggest appeasing the Kraken with groveling and assorted gifts.  His eye is upon you.  Tread carefully, my friend.

[NSEP]

Yeah its Alt/Mod/Whatever.

I use that to spin rotors for my planes actually.

[Deddly]

Looks like the question has already been answered (way to go, everyone!) but I went ahead and moved this to Gameplay Questions anyway, just for the sake of tidiness. Keep up the good work