[\begin{align} p _{n+1} &= p _n+K\sin(x_n) \mod 2\pi\newline x _{n+1} &= x _n +p _{n+1} \mod 2\pi \end{align}]

based on Complexity Explorable:
" Kick it like Chirikov -
Explore the chaotic sea of the standard map
"