Same here! My son loved spitting and playing with saliva when he was about 1.5 years old. I tried different methods to stop him but to no avail. Finally I gave up and he just outgrew it at around 2.5 years old. I guess this is just part of a child's developmental stage. You can still teach him this is not right and not hygenic as saliva contains a lot of germs and we'll spread the germs to others, and it's very anti-social as others won't play with us. However, there is no need to get agitated. It's a phase which will pass over time