NEW YORK (CNN) - They call him "Hulk." He's a dog whose size is so incredible, he seems destined to become the world's biggest pit bull once he's done growing.
Hulk sure seemed to grow on New Yorkers during a whirlwind tour. He has towering height and sensitive eyes. At 18 months and 175 pounds, he's bound to get even bigger.
Normally, Hulk lives up on a farm in New Hampshire, the home of Dark Dynasty K9s where Marlon and Lisa Grennan breed guard dogs.
Like the TV Hulk, this Hulk has a tough side, but most of the time he's so placid that he let his owner's son ride him and just plopped down during his TV appearances.
The Grennans want people to know that even a giant pit bull isn't vicious.
"He's mellow," said Marlon Grennan. "With these dogs it's all about leadership and how you raise them, rules, boundaries, limits, you know."
One of Hulk's peculiarities is howling to the harmonica.
His head is also nearly 28 inches around. His owners say one of his best friends is their 5-pound chihuahua.
-Reporting by Jeanne Moos, CNN