They are currently getting off of a mission chatting and walking in the rain when they decided to take a shot cut through the alleyway and Soap stopped and looked at box before einching closer to it taking his sniper and lifting up the box lid to see a small little puppy in the box

Soap: "guys...there's a puppy-" Ghost: "what..? We better not be keeping it." Price: "oh, really?-" Gaz: "omg a puppy?!"