Argentine way to say that something takes you by surprise. Chan is an onomatopoeic word for amazement & Lanzani is a failed Argentine actress who was dismissed by program of TV at live by Mr. Gerald Sofovich. The term was popularized and created by the tv show "Duro de Domar" by Roberto Petinatto & "El locutor". Lanzani de Chanes literally means: Lanzani of chanes. It is similar to say "Lluvia de Chanes"
Robert: Your mother suck's
Locutor: Lanzani de Chanes
Robert: xD ELO, Edgar give me a hug