Callahan, who stands 6-foot-4, 265-pounds, and is known to his teammates as "Shrek" talked with Bearcat Insider about the nickname.
"Freshman year in football everyone called me Shrek," said Callahan. "It was because they thought I was the big ogre; big ugly of the team."
It's that size Callahan looks to bring to Bearcat Nation and the offensive, with a touch of versatility.
"The coaches said they will teach me how to play center," he said. "So I can be versatile on the line."
He also spoke about the passion he will bring to Cincinnati.
"I have a lot of passion for the game," explained Callahan. "I've been playing since third grade on a traveling team at a competitive level. Playing for the University of Cincinnati, I think I can contribute a lot of passion to the game, love and attitude."
Callahan feels like a lot of the stress has been lifted off his shoulders since making his verbal pledge to UC.
"Things have got a little calmer in the recruiting process," he said. "Coaches know where my commitment is. Its stress relieving going into my senior season, I can focus on football. I know I have a good plan ahead of me and focusing on school."
Callahan held offers from not only Cincinnati but Akron, Ball State, Buffalo, Eastern Michigan, Kent State, Ohio and Toledo. Asked what stood out about Cincinnati over the other schools recruiting him, he said, "Easily close to home and wasn't too far away. I like the campus a lot, the atmosphere around the stadium and I visited a lot of other schools, where things seem out of place; distant."