When two gay men are having sex and as one of the men is about to insert his penis into the others ass the one recieving farts really hard on the head of the others cock and it makes a hissing noise.
"Greg and I were about to engage in butt-sex but he pulled off the Hissing Snake."
A trip to a grocery store, convenience store, or gas station for the sole purpose of buying an excessive amount of junk food and sugary drinks, usually with friends. A chud run often happens late at night and ends with everyone involved hating themselves afterwards.