What do "dessert nachos" made of cookies and cakes, deep-fried dumplings and a loaded double cheeseburger have in common?

They were all on the menu for the This Is Why You're Fat "Eat and Tweet" challenge to celebrate the launch of the popular blog's new book of the same name (tag line: where dreams become heart attacks).

This Is Why You're Fat tweeted the locations of six Manhattan food trucks and the first person to send in pics of all six fattening treats won a party for 25 friends from the food truck of their choice and a copy of the "This Is Why You're Fat" book by blog founders Jessica Amason and Richard Blakeley.

See what folks ate after the jump.

First up: Ice Cream Waffle Sundaes from the Waffle Truck in Midtown Manhattan. Then "TIWYF" tweeted the location of the Cupcake Stop where contestants had to throw down cinnamon buns.

The third stop had constants attempting to wrap their mouths around Bistro Burgers from the Bistro Truck at 16th Street and Fifth Avenue. The burgers, from top to bottom, were made of fried onions, a fried sunny-side up egg, garlic mushrooms, fried mortadella ham, two cheeseburgers, lettuce, tomato and bistro sauce.

Nick Ichien, a student at New York University, heard about the food challenge and had come to try the Bistro Burger. "It's really good, actually," he told Slashfood with a face full of bistro sauce. "I think I'm full after one bite."

Slashfood ran into the books co-author Amason at the Bistro Truck and she told us how they came up with the idea for the Eat and Tweet challenge. "I've been wanting to do this for a long time," she said. "I think it's great being able to connect with fans in real life."

Also on the menu: fried dumplings from the Cravings Truck, Dessert Nachos made from cookies, chocolate chunk brownies, carrot cake and Rice Krispie Treats at the Treats Truck and the "Decadent Michel Cluizel Brownie Sundae" from Van Leeuwen Artisan Ice Cream.