To go crazy.During World WAR II the Japanese became so desperate to win the WAR that they began committing suicied bombings and flying their planes into U.S ships.
If this nigga Matt keep talking shit I'ma "Jap out" in this mothafucka and beat his ass.
To not go through with something; to not go with or not show up. To bail on a commitment such as a date or promise. (Popular during the '70s..a variation on a wrestling move called a "jap-out" where you escape your opponent.)
"Ok, let's go to the mall tonight, just don't jap out on me." "He always japs out when it comes to paying for beer."