I saw this on a friends FB wall apparently from Jinkiestv and it looked like fun. I gave a Sherlockian reply (We're cosplaying BBC Sherlock).
You and I are in the back of a police car...
Using only 4 words, you turn to me and say...
(Now the fun begins. The first person to reply would state the 4 words they would say to me, CAMPer. Then so on and so forth with each additional reply being for the Sherlockian above you.)