My oscars "play dead" when ever they are stressed (like when you clean the tank out etc) they lay up in the corner of the tank & loose all their colour.
This is very common.
try checking your tank temperature (should be around 78F 24-25C)
what is his "Friend"? is he bigger then the oscar?? how big is your oscar?
sounds like a little bit of stress to me.
hope this helps,
Nick