I once had a experience with a colleague. She would continually come to me to parse XMLs and give it to her in some format like a csv which she could open it in Microsoft excel for some report generation purposes.
It started to happen pretty frequently and would consume a great deal of my time- It was reaching a stage where I had to stop my work to do her's. After a time she would just show up at my desk with her laptop, I had to write the code while she chatted with some one on her mobile. One afternoon I had, had enough and I asked her why she couldn't do it herself. She then mentioned she only knew C and C++. Then I asked why couldn't she parse the XMLs in C or C++? After a few questions back and forth, she understood I wasn't going to her homework after all.
She shed enough tears to convince our project manager, that I wasn't a good team player and I was the reason why the productivity in the project was falling down.
Thankfully one afternoon our clients had her removed from the project when I was on leave, and they made her write programs in a war room while the whole team was watching her screen on a projector.