man was allegedly bent over couch and sodomized during gruesome initiation ritual at waxahachie , texas , volunteer fire department .
the five firefighters apparently ` yelled with excitement ' during the january 20 incident and switched from broom to sausage .
fire chiefs thought to have told victim not to tell about sexual assault .
assistant fire chief said to have chuckled , said ` this is funny s *** '
alleged victim vomited in the bathroom and his would-be colleagues stole his clothes .