The phrase means that the user does not have any heroin.
Heroin is commonly heated in a spoon before being sucked into the syringe ready for injecting. The phrase therefore suggests if there is a hole in a spoon it can not contain heroin.
Used in Melbourne, Australia
"Can you help me out mate, I got a fucking hole in my spoon" said the addict to his dealer.
When you say somebody have spoon on themselve, it means they're sayin' non-sence. Slanging, They're eating crap(shit) by that spoon.
Specially when they're being curious on one's personal life or cutting on somebody saying irrelevant things.
(A Persian common urban expression)
A: I'm doing my best to buy that new PC. I do need it
B: If you need anything, just give me a call.
C addressing A&B: Don't do that! It doesn't worth it.
A replies: Do you "have your spoon on you"?!