The Life and Opinions of Tristram Shandy, Gentleman Book 8, Chapter 32 Summary
After Toby falls in love, Mr. Shandy asks him how his ass is. Toby was thinking about a blister he'd gotten from riding, so he responds that it's much better. Dr. Slop and Mrs. Shandy laugh, and Mrs. Shandy says that everyone says Toby's in love. He admits it, and says that he knew when the blister (on his ass) broke. Charming.