Praciticing machine learning Techniques.
Handling missing/no values, performing EDA, Feature Engineering and various algorithms on different datasets.
I would highly recommend that before the hack night you have some kind of toolchain and development environment already installed and ready. If you have no idea where to start with this, try a combination like:
Python
scikit-learn
/sklearn
Pandas
NumPy
matplotlib
seaborn
jupyter notebook
Here are some datasets which i work during this ml practicing.