Building a Deal With It meme generator using OpenCV can teach us a number of valuable techniques used in practice, including:

1. How to perform deep learning-based face detection

2. How to use the dlib library to apply facial landmark detection and extract the eye regions

3. How to take these two regions and compute the rotation angle between the eyes

4. And finally, how to generate animated GIFs with OpenCV (with a little help from ImageMagick)