(Noun) A rusty breeze is the odor of the anus that emmits off someones body as they walk past you, this is due to the insufficient wiping of the anus.
"Damn did get that wiff of that girls rusty breeze over there?"
"Yo last night I forgot to wipe my ass and
I had the worst rusty breeze."
Source: Jenna Ippolito and Ryan Cataldo (Joe Cats is god!), New York