This weekend, I was in a mini-van, on a road trip with a bunch of friends for a bachelor party. During the three-plus hour drive to our destination, my friend Colin had noxious gas, which he described as being "fusty." We all instantly fell in love with "fusty," and used it throughout the weekend, but believed it was a creation of Colin's fertile imagination. To our surprise, "fusty" is in the dictionary, and this is definition #1:
having a stale smell; moldy; musty
So, now that we all know the definition, please use "fusty" around your home and workplace. You'll thank me later.
"I need to clean out my lunchpail because it's gotten a bit fusty."
"With the windows closed, the apartment's smelling fusty."
"Someone dropped a fusty one in the men's room."
And to answer your question, yes, Colin's farts were fusty.