A spontaneous reaction to absolutely nothing which involves one individual of the group declaring the act and the other members acknowledging the declaration by flailing themselves at nearby walls while yelling 'earthquake party,' along with sounds that compliment the smashing of one's body into walls as if an earthquake were occurring.
Dude, I think it's time for an "EARTHQUAKE PARTY!!!!!!"
earthquake (smash, bang, crah) party (slwap, oof, DUDE!) yeah!!!!!!!