This method involves changing the date/time of your console. If you do not agree with this method, an online method is included below.1. Go to "My Games & Apps" > "Apps" > "Settings" > "Network" and then "Go offline" & "Forget Wireless Network"2. Hard reset your console by holding the power button for 5-10 seconds.3. Sign in and go to "My Games & Apps" > "Apps" > "Settings" > "System" and then change the date to any of the follow dates:January 1 - "Baby Shark Petting"October 31 - "Danger, Carnage Zone"December 25 - "Danger, This Soffish, DO NOT EAT!"4. With the changed date, load Halo MCC, select a custom game in Halo 2 Classic on Zanzibar.5. Go to the beach and look at the sign next to water.6. Go to "My Games & Apps" > "Apps" > "Settings" > "Network" and connect to your wireless connection by selecting it and entering the password. The achievement will unlock as soon as your Xbox connects to Xbox Live.This achievement is only available on 4 days of the year, as follows:January 1 - "Baby Shark Petting"July 7 - "Are you finding Ling-Ling's head?"October 31 - "Danger, Carnage Zone"December 25 - "Danger, This Soffish, DO NOT EAT!"On one of these days, in your local timezone, you will need to load a custom game in Halo 2 Classic on Zanzibar, and then go to the beach and look at the sign next to water. On the dates listed above, the sign will be unique and the achievement will unlock.