Baloney (or bologna) was what Ponyboy and Johnny ate for the five days they spent in hiding in the church on Jay Mountain. The boys ate up their supply of candy bars during the first two days, leaving nothing but bologna and bread for the final three days.
"... by the fifth day I was so tired of baloney I nearly got sick every time I looked at it."
After Dally arrives, the boys were happy to have "gorged on barbecue sandwiches and banana splits." But after the deaths of Dally and Johnny, Pony lost his appetite.
I used to eat like a horse, but all of a sudden I wasn't hungry. Everything tasted like baloney.
The bad taste of baloney still sticks with Pony, and it symbolizes the depression that has overwhelmed him and his refusal to get along with his own life and responsibilities after his friends' tragic deaths.