Madeline: Andrey was being so funny in ballet class today.
Sasha: Really? What was he doing?
Madeline: He made all of these funny faces and was trying to be "Arabish."
Sasha: HAHAH! SWL!
Same wavelength; when you are in sync with someone else to the point where your brain waves are on the same wavelength. Generally only used in text or written down as an abbreviation, not spoken.