First Episode of Season Two and Chase goes out of his way to say something no one expected.
Obviously, the bots never fully registered anything at first, until there were some quick discoveries later onwards. In the long run, the three bots figured out that 'Mommy' translates to 'Carrier' which can be used in both clean and dirty ways (in the situation of the episode, it was clean).
When they told Chase this, the police bot was extremely freaked out by this and literally thought he done something wrong (which he was assured multiple times he never did something wrong to begin with) this entire time.
That also brought Chase to remind himself of the past, making it ten times worse, so that turned into more of a major deal than it should've.
But besides that, Chase learned a very important lesson, to simply never say Mommy ever again.