I don't like making super long TL notes, so I'll just put this here instead.
For those unaware, Japanese people really like wordplay and this is especially true with numbers and dates. Anyone that looks at a lot of Japanese fanart has probably noticed that you get a lot of "Nice X Day" entries during November. This is because the Japanese word for "nice"/"good", "いい", looks like 11, so it's just a matter of making another pun off the number of the day (thus 8, which looks like a pair of boobs, becoming "Nice Boobs Day", etc.).
Here, the numbers 1 and 6 have possible readings with "hi" and "ro", respectively, so they can be read as "Hiro". Thus, November 16th is "Nice Hiro Day".