Something about this is a bit
Next to the side, I'm out of position,
For a scientist put me in a bin,
But children appear when I jump,
A bad smell means success with me in.
In sport, if you are OFF-SIDE then you are out of position. A BOFFIN is a scientist. OFFSPRING are children. I think the bad smell would be B.O., yielding BOFFO.
I may cause upset at the end,
I can be unfriendly, or even ill,
From the side is whence I shoot,
Believe me, I mean to kill.
If you OFFEND then you cause upset. Among the various nuances of "not quite right" that "off" can express are "ill-mannered" and "unwell". An OFFSHOOT comes off from the side of a plant. To OFF someone is to kill them.
Gore follows me with rotting entrails,
Rest in peace, I paid a high price,
Show to me a pretentious sort,
I have authority on the ice.
OFFAL (think Al Gore) is entrails. If something is very expensive it might be a RIP-OFF. The pretentious person is a SHOW-OFF. If you are a person with authority -- a manager, executive, etc. -- then unlike many workers you probably have your own OFFICE.
Oh, and of course the title: