In five years in the NFL, Rob Gronkowski has built a reputation for being a bruising, punishing tight end on the football field and a fun-loving, party animal off of it.

But as much as we seem to see the New England Patriots tight end dancing and partying uncontrollably, don't think that Gronk's gears aren't grinding in his head. An excerpt from his upcoming autobiography, It's Good to be Gronk, due July 14 on Simon & Schuster, reveals that Gronkowski hasn't spent a penny of the $16.3 million-plus that he has earned in his five seasons with the Patriots. 

"To this day, I still haven't touched one dime of my signing bonus or NFL contract money," Gronkowski writes in an excerpt from the book obtained by Sports Illustrated. "I live off my marketing money and haven't blown it on any big-money expensive cars, expensive jewelry or tattoos and still wear my favorite pair of jeans from high school. I don't hurt anyone (except Gord with the occasional kick to the groin), I don't do drugs, I don't drive drunk, I don't break the law...I'm a 23-year-old guy (now 26) just looking to have a fun time."

It's pretty impressive that Gronk says he is living off his endorsement deals, which have included Dunkin Donuts and BodyArmor, and has saved his NFL salary. He has a lot more of the latter coming, considering the upcoming 2015 season will mark only the third season of the six-year, $54 million contract that he signed back in the 2012 offseason.

This all goes to prove the old adage right—don't judge a book by its cover. Not only are we pleasantly surprised to hear that Gronk is stacking up on his cash, but we're proud of the guy. See...he's not just a frat boy football player/dancing machine.

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