Christmas Day. Brand new Nintendo Wii with a copy of Super Mario Galaxy. Changed me life it did.
Tied between two in my memory gaming wise
My grandmother bought me SA the year it came out for Christmas. VC had been one of my favorite games so I was super excited. She let me open it a week early and play it for a few days without my mom knowing. I gave it back so she could wrap it. I still remember jumping on that bicycle for the first time.
Other one was when my mom got me a PS3 for Christmas. My family never had money so I never expected it. Opened it on Christmas and cried. I proceeded to tell her she can return it because I figured she needed the money. I told her I would use my allowance I had saved up. She refused.
I remember one off the top of my head. Well since GTA IV is banned where I am from, I was devastated I couldn't get a copy. So one of my friends came to my birthday event and just gave me a bag. He told me to check what's inside after event, so sticking to his word I did. Once the event was over, I remember just playing a very bad PS3 game (I think it was LOST haha) when I remembered the gift. I opened it up, and once I saw Niko's face on the front cover, I went crazy. I popped in the disc and paced all around my house while the disc was installing thinking about the features and how much fun I would spend in the game. Wasn't disappointed.