Running with a foam cheeseburger around your waist is hard enough. Then come the catcalls.

"I got 'Nice buns!' and I got 'Where's the beef?'" explained John Koss, the 28-year-old Boston resident, who endured that and more R-rated banter thanks to a gigantic cheeseburger -- complete with lettuce, tomato, and onions -- strapped to his waist as he trekked the 113th Boston Marathon in 4 hours, 34 minutes, 29 seconds Monday.

Koss agreed to be a human toothpick for the local B.Good burger joints in order to raise money for the Run for Research foundation that benefits the American Liver Foundation.

"In a year like this, when donations were hard to come by, we looked for everything and B.Good was good enough to work with us," said Koss. "The challenge to me was to actually finish in this."

Running his second Boston Marathon was decidedly more difficult than the first (which he ran sans beef). The burger tutu didn't exactly weight him down, but it proved to be quite bulky, particularly in crowds.

Racers and supporters had a good time with Koss, who enjoyed the supports (and jabs) from the crowd.

"The kids, that's the best part, the kids' faces," said Koss. "I don't know if they have it any more but, Mayor McCheese, (I'm) kind of like the life-sized version of Mayor McCheese."