Stable mapping from current day to a random day in HN past:

data:text/html,<script>
const b = new Date(2007,1,19);
const d = Math.floor((new Date().getTime()-b.getTime())/864e5);
let h = d; h^=h>>>16;h*=0x7feb352d;h^=h>>>15;h*=0x846ca68b;h^=h>>>16;h>>>=1;
const p = new Date(b.getTime()+h%d*864e5);
window.location.href = `https://news.ycombinator.com/front?day=${p.getFullYear()}-${p.getMonth()+1}-${p.getDate()}`;
</script>

Different day on every invocation:

data:text/html,<script>
const b = new Date(2007,1,19);
const p = new Date(b.getTime()+Math.random()*(new Date().getTime() - b.getTime()));
window.location.href = `https://news.ycombinator.com/front?day=${p.getFullYear()}-${p.getMonth()+1}-${p.getDate()}`;
</script>

To use, save the script as the url of a bookmark.

I appreciate it a bit more this way..