I think our EE pullet, Dragon, is part kangaroo...or something. She'll be 6 weeks old tomorrow, and has been outside with her flockmates (same age) for two weeks. However, we would periodically bring them outside to forage and run amok for a few hours at a time since they were a week old. Ever since we've been bringing them out, she has this run, hop, bounce in place things she does with the others...it typically occurs right after we'd bring them out, or as is now the case, when they all pile out when we open the coop in the mornings. They all pile out and literally run all around the run bouncing, flapping, flying, and acting like, "Weeeeeeeeee!!! We're free, we're freeee!" and then somewhere in the midst of that Dragon will run head on at one of the others, come to a screeching halt right in front of them, and hop in place. This always results in whoever she charged hopping in place and then they will exchange bounces for a few seconds before going about their business. Dragon is always the one who instigates the bouncing. We've never seen anyone else start it, though they will all respond the same way when she does it. It's quite hilarious to watch, and no pecks or physical contact of any kind is ever exchanged during the "process", but what in the heck is going on?