Where to begin...
Algebra.
Overstating the obvious: I do not own this South Park gif thing.
Here is an accurate (albeit animated) depiction of my 9th grade algebra class experience. Add a teacher who liberally punctuated her instruction with a speedy “uh-KAY?” every few syllables and you might begin to understand my bewilderment. Geometry I LOVED. Algebra? Still stuck as reflected in my GRE math scores.