When I got Level 50 Skill Rank in Halo 3. Easily my most favorite console game still to this day. I played so much Halo 3 on my main account I maxed the EXP out so I was a 5 Star General by no time. It was a coveted rank back in the day, wanted by boosters and feared in social lobbies (back when skill ranks were shown in pre-game lobbies right on your gamertag nameplate).
Halo 3 may be gone but I saved the Bungie.net web pages and have my past gameplay recordings. I still destroy lobbies in Halo MCC. Once you reach that level of skill it sticks with you forever translating across other fps's. Once a Halo 3 General always a Halo 3 General.
I remember those, one of the few times in my gaming lifetime I was willing to help and join random parties of randoms was to get those Vidmaster challenges done with them.