The first one is from a song by a 90s boy band. The actual line is "it's gonna be me", but it gets misheard a lot because of the way he pronounces it so it's been grouped in with a few other date memes like April 25 and October 3rd. I think most of the appeal is just that you can only use them once a year.
The second gif, I have no idea where it comes from, it just came up when I was getting the first one.