The act of rushing to the toilet unsure of it being a false alarm (fart) or actual shit. Once on the toilet the anus lets out a small fart crescendoing into a massive vibration and finishing with shit coming out in the end.
Guy 1: "Be right back man, i don't know if this is a fart or shit"
10 minutes later
Guy1:"Yup it was a shit bomb"
Guy2:"Holy shit i thought it was an earthquake"