Algodoo

glith one egg have a second hinge whit 0% of opacity!

It's not a glicth, you put a spring connected to both of them with -0.10 damping you liar!

@Phun User -- MoBuilds explained it the scene description, and he did not lie because springs really do become unstable when you give them a negative damping value. That's a GLITCH!

@Xray, it's not really a glitch to me since it's most common in my engines.

Hehe, this is one of my favorite bugs, the negative damping springs.
Please do not fix it. It is way too useful ;p

Wait. isn't this intended? Like,
+damping = slow down connected
∴ -damping = speed up connected

The absolute damping seems to increase exponentially(?) Would explain the bugging out as caused due to accelerating too rapidly and going too fast for Algodoo to handle. (Just like negative air friction)
Therefore you have to be very careful when using negative damping as without air friction, it will increase to a REALLY fast speed.
I've sometimes used negative damping to counter air friction with an oscillating object whilst also keeping the air friction of an object after the spring is removed. Yes, it's more hacky than just using a bit of clever scipting and OnDie or something but hey, whatever worked.

Now what DOES look a lot like a glitch is negative density; just try it yourself, kinda hard to explain it. Objects get sticky, float downwards, weird stuff. Hardly even makes sense, unlike the negative damping of a spring. I mean, it shouldn't even be possible to have negative density, we know nothing of how it would be like. Do they speed up with air friction? Repel with attraction? How do we decide which components are inverted? Why and how did I even get into negative density while we were talking about springs?