Flip-flops or thongs. The Japanese wear these a lot and when you walk they slap your foot.

definition 1: When you slap someone with your penis, normally around the face.

Definition 2: To be slapped on the end of the penis.

Superman Jap Slap is when you perform the martial arts move of the “Superman Punch” but instead of punching, you slap your opponent with an open palm moving in a downward diagonal motion right-to-left (for right handers).

A confluence of horrendous disasters befalling one or more people in a short space of time.

A devious sexual trap involving a females genitalia.

An oriental massage parlor where men go for a hand-job and massage by an asian.

It means multiple things. Basically, its a WWII reference, meaning:

1. Karate chop. Japanese were known by soldiers for their superior hand to hand combat skills, particularly in karate.

2. To strike a person unexpectedly, similarly to a sucker punch.

3. Loosely, it refers to an unexpected attack or ambush.