[alexander_busek]

There is an old expression “You’re on the needle, man.”

And what does that old expression mean?

Regards,

[right way right]

You’re on Heroin, drugs, etc. That’s what it means.
“On the needle”
Not directed at you.

[chaosagent]

Don’t know for certain, but I suspect it has to with aircraft navigation, where you ‘fly the needle’.

So when you’re “on the needle”, you’re on course.