"Inum" (isn't them / aren't they) is an informal word, similar to innit which is used to complete a sentence that doesn't need completing.
Also used to confirm that what you've said is true and to leave the line open for further communication.
1. "I'll come round your flat this afternoon inum."
2. "Lol I'm totally drunk inum!"
3. "They're completely bonkers inum!"