Short Answer: "Sadede gel." means "Come to the point" Long Answer: Generally, people ask "Lütfen sadede gelebilir misiniz?" or more directly and agressively "Sadede gel, sadede!". The word "sadet" came from Arabic to Turkish language. 'Sadet' means "The main subject of the conversation" or "the matter". With adding dative case '-e' suffix, "sadet-e", it become "sadede". The 't' turns to 'd', regarding to "consonant softening" in Turkish. So "sadede gelmek", to stop talking about irrelevant things and to say the thing that we want to say actually. We use it like "what are you trying to say? Just say it!" or similar to "Spit it out!". Example: the family are together to talk about an important situation, they've started to talk gossip about it. And after 5 minutes their father says, "Neyse, bunlar hep dedikodu. Sadede gelelim.".

come to the point, get to the point