When I was a child, I loved to fill out things in workbooks and magazines for children. When I started going to school, I loved to fill out things in course- and workbooks and today I love doing so as well. No wonder, I have collected English coursebooks and workbooks throughout my whole education. Those were not only my personal ones, but I also have a collection of my brother's English coursebooks and some of my mother's as well. Some of my friends have also been so kind as to give me their coursebooks. So, as you can see, for us, (future) teachers, it can be pretty easy to get to materials on certain topics. And the best thing is that you can re-use these as many times as you want.
This is a worksheet I found in one of my mom's books not so long ago and I loved it immediately. If you are teaching a lesson on etiquette in certain situations, you can use this worksheet and have a laugh together with your students. It is actually a dialogue between two people talking over the phone and they are using a really inappropriate language. Your students have to reformulate the dialogue to make it more appropriate. You can also ask them to act it out.
Do you recycle your teaching materials? And how about your coursebooks? Do you always stick with the same, or do you combine many different ones?