I was sitting at a table in Nicaragua on a mission trip with my church. we were all talking and socializing and having a good time. so a friend brought up the topic of lucid dreaming. I said "Yeah I can never tell when im dreaming in a dream. Ive been trying for years." Then my friend says (picking up his water bottle) "The way I can tell if im dreaming is when I throw the bottle away from me, it will come right back." So he throws it and it just acts normally as it would in RL.