Chicken and repair

There was a Chinese father named Cheng who was very close to his son. They used to go everywhere together including looking for "chicken" (Chinese slang for prostitute).

One day, Chung, the son decided to go overseas for study. The father was very supportive, and before his son left, the father told him, "Chung we cannot look for chicken together for the next few years. However, if you need to look for chicken, please go ahead and I will pay for it. But please state the expense as 'Shooting Bird' so that your mother will not suspect."

So the son left, and after a month, the father received the bill from Chung, the son,......(shooting bird - $500).

Subsequently, and for the next few months, the bill for shooting bird is more than $1000. Well, the father could not tolerate this, so he wrote to his son.

"Chung Son, you have been shooting too expensive bird, try some cheaper one".

A month later, Cheng, the father, received another bill from his son. On it he had written: Shooting Bird - $50, Rifle Repair - $2,000