In the prior scene, Rex is tempted by an older female canine.
He then has the following exchange with his owner:
Owner: Rex, what are you doing?
Rex: Well, I would say that I’m just drifting. Here in the pool.
Rex: Well, it’s very comfortable just to drift here.
Owner: Have you thought about graduate school?
Owner: Would you mind telling me then what those four years of dog obedience school were for? What was the point of all that hard work?
Rex: You got me.