How the rodent gets there is very usually a non-accidental state of affairs - despite whatever protestations to the opposite the sufferer may claim. e.g. "I slipped over in the pet shop and fell down in bucket of gerbils."
The rodent's death throws as it suffocates are alledged to give pleasure to the 'gerbil stuffer'. Sometimes, other rodents such as a mouse or hamster are analy inserted too.