Bender flushes Nibbler down the toilet, but the Professor fits him with a chip that makes him feel Leela’s emotions. So they head to the sewers to find Nibbler.
Nah, good guess but Bender flushes himself in that one and Leela and Fry go looking for him. I think this is Luck of the Fryish, when they went looking for Fry's seven-leaf clover.