An employee asks her co-worker to take over her shift

— Paul, could you cover my shift for me on Friday? I'm flying to Las Vegas for the weekend, and I could really use the extra day off.
— Sorry, but I'm scheduled to work that day. Have you asked Lacy? She's always looking to get more hours.
— Yeah, I did. But she has a dentist appointment on the same day.
— Why don't you take the next Monday off instead? I can work that shift for you, and you can still get a three-day weekend.