- "I started rapping way back in the day...."
- — Mark Grigsby
Mark Grigsby was a former Lead Animator and currently Animation Director at Infinity Ward. He lent his likeness and voice to SSgt. Griggs in Call of Duty 4: Modern Warfare, and sings the "Deep and Hard" during the credits.
- "I started rapping way back in the day. I had a crew and everything. But my passion was animation, so I had to leave my crew and do my thing."
- "They were looking for inspirational songs for the end-credits. I definitely love Boot Camp Click and love Sean Price, so I'm like 'Let's get a Sean Price.'"
- "I still rap here and there."
- "We wanted something more personal and everybody wanted me to do it. So I did the end-song credit."