Jimmy is a young woodchuck in a cutaway gag set up by Stewie when he vows to attract the attention of Landon's mother in "Fighting Irish".
As Jimmy tells his parents that he would rather become a doctor than go into the family business, he father brings to his attention just how absurd it would be if people said "How much disease could a woodchuck doctor cure if a woodchuck doctor could cure disease," rather than the proper phrase. As Jimmy agrees on the ridiculousness of the phrase and starts to leave, his dad reminds him to test any future ideas he may get before bring up such a subject in the future.
Jimmy joins several other animals of the show as well as the cast in singing "Blue Shadows On The Trail" in "Wild Wild West".