sneaky, like a ninja.
also, cold and calculating.
resourceful, a la MacGuyver.
I couldn't shoot him in paintball because that spivey m-effer just vanished into thin air.
You never know what he'll do; he's spivey like that.
We didn't have the tools we needed to fix it, but since Buster is as spivey as MacGuyver, we were soon back on the road.