If a Buddhist gets offended by a joke about Buddhism, then they are not doing very well in their practice. (I say that as a Buddhist).
Actually the joke just represents a fallacy about Buddhist doctrine which doesn't actually teach about "being one with" anything. It is more akin to Vedic (Hindu) teachings.
Sorry about the tangent, I shall go out with a lame joke:
Three statisticians went duck hunting and finally came across a duck. The first one shot at it but aimed too high and missed. Then the second one shot but aimed too low and missed. The third one jumped up and down all excited and yelled "We hit it we hit it!"