I know what it meant years ago. 
That meaning doesn’t seem to fit the song.
manager is on the phone for a slice of that poon. Agents beefing in 10% of that poon, drummer wants a raise, promoter wants a taste. Give me that poon
Money seems like what he’s talking about.
Is that word slang for money now?
It’s a funny song. Lots of double meanings.
I’d swear he’s talking money.