Hacker News Reader

The ^HA (laughing at the image above) is just... wow, even the person running the Twitter account thinks it's bad.

Apologies if you're joking but that's how they sign off their tweets—HA is the initials of the person replying.

I believe those are the initials of the rep who answered.. their reply tweets have a few different ones like ^NR, ^CM, ^SK.