Dr uses a 4 letter word

A man is recovering from surgery when a nurse asks him how he is feeling.
"I'm OK. , but I didn't like the four-letter-word the doctor used in surgery," he answered.
"What did he say," asked the nurse.
"I'm OK. , but I didn't like the four-letter-word the doctor used in surgery," he answered.
"What did he say," asked the nurse.
Spoiler: