"Scheise" is the anglicized spelling of the German "Scheiße" (with "ß" being the German letter representing the double "s" sound). Its English translation is "shit". It is often used (much like in English) as an expletive.
Any instance in which you would use the Englishword "shit" (again, especially as an expletive), one can substitute "scheise" or "scheiße". While not exactly scholarly references, one can hear the word used in film in the movies "Bourne Identity" (spoken by Bourne's German girlfriend) and "Austin Powers" (spoken by Dr. Evil).
Someone who jumps from one relationship immediately into another one.
Serial monogamists can not stand to be alone and often suffer from vast commitment and insecurity issues.
Because they jump into relationships immediately after the previous one has ended, serial monogamists typically don't take the time to reflect on their behavior or why their previous relationships failed; thus, they end up making the same relationship mistakes over and over again.
Person 1: Damn, Dustin already has a new girlfriend?! It's only been two weeks since he broke up with his fiance! I think he's a sociopath.