Take any book on homological algebra, and prove all the theorems without looking at the proofs given in that book.
Homological algebra was invented by Eilenberg-MacLane. General category theory (i. e. the theory of arrow-theoretic results) is generally known as abstract nonsense (the terminology is due to Steenrod).
Source: From Serge Lang’s Algebra (editions 1 and 2 only)
Credit: Rob
So I planned to publish a book on homological algebra with only 5 pages. And all these students will appreciate me.lol