The phrase "was lachen sie" in German can be interpreted as a question "What are they laughing at?" or "What do they laugh at?" depending on the context. Additionally, the phrase is also known as the title of a well-known Austrian cabaret and comedy program "Was lachen Sie?" featuring Heinz Marecek and Erwin Steinhauer. This program includes comedic performances and has been performed multiple times, celebrating traditional Viennese cabaret culture.

Thus, "was lachen sie" could either be simply a phrase questioning the reason for laughter or a reference to this specific cabaret show. If the question intends one of these specific meanings or a contextual explanation, please specify.