The most skateboard shove-its in 30 seconds is 33, achieved by Gabriel Pena (USA), in Houston, Texas, USA, on 5 September 2013.

This record was broken on the Guinness World Record Challengers site (Challengers’ tag: theskaterg): http://challengers.guinnessworldrecords.com/challenges/50-most-skateboard-shove-its-in-30-seconds/attempts/4289