Well, "realism" is a pretty ambiguous word, so depending on your needs it could be any number of solutions. I think the best you can do is photograph a few of those pocorny thingys and use them as custom particles. You would have to animate the tumbling in a pre-comp since Particular doesn't handle that part for you. Then just animate the emitter's Particle/sec. setting from a very high value to zero, but over a very short period of time (5-10 frames at best). This will give a nice popping effect. Make the Velocity of the particles very high (because they are so light), but use Air Resistance, Wind and Gravity to slow them down and move them where you need to. Lastly, youse a high Bounciness setting on your collision plane so the puffs jump around a lot. If you can live with some less realism, you can build interesting custom particle shapes using effects suzch a Fractal Noise, Roughen Edges and Circle. Also think of Particular's Cloudlets/Smokelets. If you apply a Posterize or Levels effect after Particular, it will increase the contrast between bright and dark areas and give you a slightly cartoony version.