It's an intro scene:
Jerry asks George if he was captured by aliens, which would he prefer - to be in their zoo or their circus. George replies "I gotta go zoo" Jerry says why, and George explains that if he was in the circus, he'd be travelling around, doing all kinds of tricks, but if he was in a zoo, he'd maybe get a member of the opposite sex in with him, for breeding. Jerry says, but what if you don't get a female for sex? George replies: "Well, then I'm the same as I am right now. But at least I got a ride in a spaceship."
It's a great scene but I can't find it on any of my tapes.
Thanks GPD