I just found the fist bump gun buddy in my collection today and I’m confused where it came from. Does anyone know how I would have recieved it?

I wanted to make a quick list of the biggest factors that helped me grow as a player and get huge win streaks. I started the game placing in bronze 2 and climbing to gold 1 that act. Then G2, then P3 and then Diamond 1 hardstuck for 4 acts....