This word is kinda ironic, because it's normally said with a smile and a happy recollection of all the grubbles you tore through (i.e. even though the word sounds a little narsty, the connotation is not one of regret or remorse, but rather guilty satisfaction)
"I need to get some exercise, dude. I was mackin down at that BBQ yesterday. It was a total shlard-fest".