Anybody have any ideas?

Kick? Snooker balls are made with a very hard outer surface so as to transfer virtually all momentum to another ball on contact. The game would not work unless that happened. Is that what you meant?

good question!
i'm curious too. my guess is "stiction". (see Wikipedia - sort of "sticking + friction")
i'm a little surprised it hasn't been nailed yet.
if it is stiction, cleaning the balls wouldn't help much. willie thorn was saying it didn't happen so much in the past, with heavier balls & thicker cloths. i would suspect the material of the balls as the most obvious - needs experiments with different materials. i would suggest PTFE, at least for the cue ball.

Players use chalk on their cues and if it happens that the chalk mark on the cue ball is the bit that contacts with the object ball then you can get unexpectedly high friction during the contact, causing a "kick." It's also why quite often you'll see the players asking for the cue ball to be cleaned after getting a kick.

The new show on Discovery Channel "Time Warp" has an episode with billiards (this side of the pond!). You may be able to find streaming video, which, even if it doesn't completely answer your question, you'll enjoy, I'm sure.
Peace,
Ron

We have carried out a lot of experiments into this phenomena...

SNOOKER BALL 'KICK' RESEARCH - 'Nothing' is to blame.
One of the great phenomena of snooker. The kick is where either the cue ball or the object ball literally jumps in the air slightly after receiving contact from the cue or the cue ball respectively. The effect is nearly always negative for the striker, as the angle on either ball is disturbed and contact is rarely clean. Many attempts have been made to explain why kicks occur, the most frequent explanations being friction from the table surface and, more commonly, a bit of dust or chalk on either ball when there is contact.

We believe that 'nothing' actually causes this phenomena. Using our Magmascope Gamma-Blast Absorption Apparatus, we have been able to witness and capture the precise moment that the Kick occurs. During the event ( 0.812 milliseconds) we also took spectrographic, electromagnetic (full-spectrum) images. Within 4 seconds of the 'kick ' we took readings for residual Gamma, Beta and Alpha particles using a Geiger-Müller counter.

Using all the equipment available at The Foundation we found no cause for the 'kick' whatsoever. This led us to the only possible conclusion.....

'Nothing' causes this phenomena.

Reginald Denke Foundation