Curt Lemon had always been scared of the dentist. Before he goes in to the tent, he passes out. After waking up and realizing he "chickened out" of getting a checkup, Lemon fakes a toothache and makes the dentist pull the tooth to prove he is not a coward.
Man v. Society
O'Brien has shot an innocent looking man cannot seem to stop staring. He creates a backstory for him. The young man loved math and was never able to fight in school, worried that he was a shame to his family and village. His pretend story relates with O'Brien who thought he would be a shame to his family and country if he did not obey the draft.
When Curt Lemon died, Rat Kiley didn't known what to do with himself. He and the soldiers find a baby water buffalo. Kiley acts gentle at first, then starts shooting the calf until it was on its death bed.
After receiving a notice that he would be going to war, O'Brien debates between obeying the draft (going to kill people though he's against war) or running away to Canada (possibly being a disgrace to his family and country.