Examples of funny graphs

Question

In order to arouse interest of my high school students to plot graphs I want to plot interesting funny graphs such as the one of the batman equation. I'm looking something simpler, maybe in a form of a piece-wise function.

I want to plot it in class.

Answer 1

Though it's not funny, but one of very beautiful graphs is "The Love Graph".

\begin{align} &x =16\sin^3 t \\ &y = 13\cos t -5\cos 2t -2\cos 3t -\cos 4t \end{align}

Answer 2

$$y = | \sin(x)| + 5\exp(-x^{100})\cos(x) , -\pi < x < \pi$$