What does Asian swamp eel mean?

Asian swamp eel meaning in Urban Dictionary

A common practice between friends in Japan resulting in one friend slipping an eel into another friend's rectum. It is most commonly done as an old traditional drinking game in which the first person to pass out is the lucky recipient. Daniel Tosh loves this prank, especially because it results in massive internal hemorrhaging and dehydration thus resulting in death due to hypovolemic shock.