He does that a lot, getting in on the act. In the nightclub scene in Robocop he was dancing like a lunatic trying to get everyone else going, they turned the camera on him and used a tiny bit of it in the finished movie.
You know the bit just after Leon Nash kicks Robocop in the plums and there\'s a \'dong\' sound, one of the next shots is an extreme close-up of a loon dancing for about a second, just a head and shoulders shot, that\'s Verhoven!!