[A grimace crosses Okuyasu's face at that question.] Oof, this's always tough to explain... [He attempts to remember the way Keicho described it to him, way back when. Okuyasu figures if his brother managed to find a way to word it so even he could grasp the concept- that's about how he should describe it to Venkman.]

...right, so- think of it like... you got control over a ghost, and you can do cool magic stuff with it- but what kinda stuff it can do depends on the person. If that makes sense.

You askin' 'cause you got one and didn't know that's what it was, or 'cause you're just a normal guy?