Hands up if you forget birthdays all the damn time. Hey, whoa, slow down. I can’t see all of you at the back. Waaaaay too many hands. Wait. No, OK, hands down. Let’s do this differently.
We’ll forget about the counting bit, and just assume that pretty much everyone forgets birthdays and ends up hating themselves just a tiny bit more each time. Especially when a few months later, the person whose birthday you forgot remembers yours, and sends a perfectly judged gift too. Dammit.