mosh pit. slam dancing

[Barnhart]

>From The Barnhart New-Words Concordance:
mosh, v.i. ..........................................   DC Vol. 8.3
                                                        ANW Vol. 68.4
          n. ............................................       DC Vol. 8.3
mosher ..............................................   DC Vol. 8.3
moshing .............................................   LRNW
                                                        BDNE3
                                                        ANW Vol. 68.4
mosh pit ............................................   DC Vol. 8.3
                                                        ANW Vol. 68.4


The Barnhart Dictionary Companion (Vol. 8.3, c.1993) shows _moshing_
(1987) and suggests that the origin may be in _mosh_ (OED, a variant of
mush, meaning to pulverize; 1848).  Mosh pit was found then (at the
time of publication, 1993) no earlier than 1990.  FWIW.