ignoring people while reading

I experienced this many times too but my friends understand that if I am reading a book then they already know that I could not be and should not be disturbed because they also know that I always focus on what I read. I am considered a book worm in all of group of friends. They know that I am an avid reader and I am grateful they understand me because they dont get offended if I wont be able to attend to them. They usually wait for me when I finish a book. Sometimes if there's something really important that they need then I also stop reading at a certain paragraph or sentence. I dont wanna stop at some point that it would be hard for me to remember or look for the sentence or page where I stopped reading.