Humorous jokes, what is "white collar" and what is "blue collar"

What is a white-collar worker? Today, I paid my salary, paid off the loan, paid the rent, utilities, bought oil, rice and instant noodles, felt the money left in my pocket and sighed: this month's salary is white-collar again. The foreman said it was almost time to get paid. As soon as he calculated the accommodation, meals, lost time and medical expenses, he still owed his boss 100, so he was too lazy to take it. He is called blue collar ~