You'd think that with John H. Conway around, this should be like shooting fish in a barrel. One title that comes to mind is 

* The Sensual (Quadratic) Form

and there are more goodies if you look at his <a href="http://www.math.princeton.edu/WebCV/ConwayBIB.pdf">bibliography</a>. For example, 

* Character Calisthenics 

or 

* The $\sqrt{\text{Monster}}$ Construction 

I also like the paper (both the title and the contents!) by Andreas Blass, 

* <a href="https://arxiv.org/abs/math/9405205">Seven Trees in One</a>