We describe a dynamic graph generator with overlapping communities that is capable of simulating community scale events while at the same time maintaining crucial graph properties. Such a benchmark generator is useful to measure and compare the responsiveness and efficiency of dynamic community detection algorithms. Since the generator allows the user to tune multiple parameters, it can also be used to test the robustness of a community detection algorithm across a spectrum of inputs. In an experimental evaluation, we demonstrate the generator's performance and show that graph properties are indeed maintained over time. Further, we show that standard community detection algorithms are able to find the generated community structure. To the best of our knowledge, this is the first time that all of the above have been combined into one benchmark generator, and this work constitutes an important building block for the development of efficient and reliable dynamic, overlapping community detection algorithms.