Algodoo

The poor clown face gets constantly annoyed by a swarm of houseflies. They attack and land on him, and he tries very hard to shake them off. Start the scene, then sit back and watch what happens over the next few minutes.

Now, here's a real head-scratcher for you programming wizards who like to try to figure out strange anomalies....
This scene was made without any Thyme scripting, and it was made without any Algodoo motors, thrusters, or any other form of mechanical devices that seem to be driving the movements of the clown. There are no hidden devices, and I did nothing funny like changing the wind direction or messing with the gravity parameters. What you see in the scene is all there is! So, someone explain in the comments how the clown shakes the flies off of himself. The first person to figure it out will win bragging rights here on Algobox! Go get 'em, Tiger!

UPDATE: Clown would occasionally shake so hard that it would shoot through the barrier wall into deep space, and so I increased the sim frequency which should reduce the likelihood of that happening.