What in the world is a "mosh pit"?!

Trav and I were asked to chaperone at the stake dance the other night.  We were told to walk around and make sure the kids weren't "moshing".  What in the world?  Where have I been?  I am officially old.  Bummer.  So... if you don't know what moshing is either, you must be old like me.  ha ha.  Moshing, is, if I understand it, is jumping and pushing and shoving each other.  Nice, huh?  Something to pass on to our grandkids.