Simply a funny way to say 'Bye' instead of the traditional "Goodbye". Usually used by people who want to leave the other person with a big question mark on their head.
From The Hilarious Hit Movie Starring Paul Rudd. "Laytress On The Menjay" was uttered by Paul Rudd's Character Peter Claven while trying to be cool and hip but FAILED miserably when asking himself "what..what did i just say?" after he said Laytress On The Menjay.
Paul Rudd: Yeah i'll be there, i'll be there.
Jason Segal: Alright, see you there man.
Paul Rudd: Alright......LAYTRESS ON THE MENJAY.
Paul Rudd: ................what ...what did i just say?