I think this manicure is actually pretty cute, rather than ugly. But it's the perfect pairing for your somewhat humiliating sweater.
I used a dark teal nail polish and opted for red as an accent. Then I took a white striper to create different shapes and designs. My advice when re-creating this look is to be patient! Take your time with the design because it can get messy. However, a few smudges isn't so bad because it mimics the look of something your great-grandmother hand-knitted (not perfect but still distinguishable).
I would also suggest getting inspiration from Pinterest for different patterns.