Man, when I was 17 and 18 years old in high school working retail, I got called in a lot. I went every time. It paid off in the end. When I graduated from high school, I told my manager, "do you remember every time I came to work on my day off?" She said, "yes." My reward? I got the entire month of June off after graduation and went on a 7 day cruise, spent a week in Florida, then went fishing at Lake Guntersville.
That winter I was 18, we had a snow day from school. About 6 inches or so of snow plus icy roads. (We live in an area where snow plows are the last to touch.) I woke up at 9am started playing xbox and my mom answered the phone (I didn't have my hearing aid on at the time.) and gave me the phone. Turns out, despite working the night before and driving home in a blizzard, some lady didn't wanna go to work because she was afraid of wrecking her car. I went and cover a grown lady who didn't want drive in the icy road and I live on a backroad... I made it to work on my day off (both school and work!) working cash register, unloading a truck, etc. I do it because i want people to owe me favors, then when they don't return me favors I don't do them anymore favors. It makes working with lazy people bearable. If you ask me come in on my day off and I do, but then I ask for something in return and don't get it, don't bother asking me next time.